Application of a basin management approach to groundwater utilization in the Otavi Mountain Land, Namibia

Physics and Chemistry of the Earth 33 (2008) 913–918

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Physics and Chemistry of the Earth j o u r n a l h o m e p a g e : w w w . e l s e v i e r. c o m / l o c a t e / p c e

Application of a basin management approach to groundwater utilization in the Otavi Mountain Land, Namibia P. Heyns * Hey­ns Inter­na­tional Water Con­sul­tancy, P.O. Box 22184, Wind­hoek, Namibia

a r t i c l e

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Available online 4 July 2008 Key­words: Aqui­fer man­age­ment Basin man­age­ment Ground­wa­ter allo­ca­tion Stake­holder par­tic­i­pa­tion

a b s t r a c t The pur­pose of the paper is to pro­vide an anal­y­sis of sus­tain­abil­ity issues related to the practical imple­ men­ta­tion of the con­cept of basin man­age­ment with ref­er­ence to the Karst Water Man­age­ment Body (KWMB) in Namibia. A river basin is regarded as an appro­pri­ate man­age­ment unit and the con­cept of estab­lish­ing basin man­age­ment insti­tu­tions was intro­duced to achieve the objec­tives of sus­tain­able nat­u­ ral resources man­age­ment in gen­eral. How­ever, the karst aqui­fer is unique because it lies in the head­wa­ ters of a num­ber of river basins and the man­age­ment of this ground­wa­ter resource goes a little beyond the logic of water resource man­age­ment as it is under­stood for sur­face water sources. In view of the unac­cept­abil­ity of the per­ceived top down man­age­ment of water resources, a need was iden­ti­fied for a par­tic­i­pa­tory approach to inte­grated ground­wa­ter resources man­age­ment in the Ota­vi Moun­tain Land in Namibia. After con­sul­ta­tions with the Gov­ern­ment of Namibia (Gov­ern­ment), the KWMB was estab­ lished to assist stake­hold­ers who obtained water for domes­tic use, min­ing and irri­ga­tion from aqui­fers in a kars­ti­fied hy­dro­geo­log­i­cal envi­ron­ment located in the Ota­vi Moun­tain Land in north­ern Namibia with the man­age­ment of their water sources. The karst area has been declared a ground­wa­ter con­trol area by the Gov­ern­ment and pro­vides the frame­work for effi­cient and sus­tain­able man­age­ment of ground­wa­ter resources. The even­tual sus­tain­abil­ity of a basin man­age­ment insti­tu­tion depends on the jus­ti­fi­ca­tion for such an insti­tu­tion, the capac­ity of the stake­hold­ers to drive the required activ­i­ties, the resources at the dis­posal of the insti­tu­tion and numer­ous other fac­tors beyond the con­trol of the insti­tu­tion. The paper dis­cusses the practical appli­ca­tion of the prin­ci­ples and con­cepts of basin man­age­ment, the chal­lenge of stake­holder par­tic­i­pa­tion, the impact of Gov­ern­ment pol­icy and leg­is­la­tion as well as the sus­tain­abil­ity of the basin man­age­ment insti­tu­tion. The paper dem­on­strates that man­age­ment of sur­face water basins and ground­wa­ter aqui­fers are dif­fer­ent in nature and require dif­fer­ent man­age­ment approaches. © 2008 Elsevier Ltd. All rights reserved.

1. Intro­duc­tion The occur­rence of dif­fer­ent sources of water such as rain­fall, sur­face water in riv­ers, lakes and wet­lands, as well as the water stored in aqui­fers, are not only related to the hydro­log­i­cal cycle, but linked to each other. These resources are also affected by the bio­phys­i­cal envi­ron­ment and human activ­i­ties. The devel­op­ment and man­age­ment of water resources are dic­tated by tech­ni­cal issues such as the avail­abil­ity of water, water qual­ity, water allo­ca­ tion, water use, efflu­ent dis­posal, and water con­ser­va­tion, as well as the envi­ron­men­tal and socio-eco­nomic issues which must be con­sid­ered as an inte­grated whole to sup­port sus­tain­able, equi­ta­ ble and effi­cient use. This means that an inte­grated approach is required when plan­ning the devel­op­ment of water resources for human ben­e­fit in such a way that envi­ron­men­tal sus­tain­abil­ity is

* Tel./fax: +264 61 252066; cell: +264 81 1284400. E-mail address: hey­[email protected] 1474-7065/$ - see front matter © 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.pce.2008.06.028

main­tained. Inte­grated water resource man­age­ment is there­fore a pro­cess aimed at the coor­di­nated man­age­ment of water, land, envi­ron­men­tal and other related nat­u­ral resources (Global Water Part­ner­ship, 2000). A drain­age basin and its nat­u­ral resources form a uni­tary whole and the log­i­cal approach is that a water man­age­ment insti­tu­tion should be estab­lished at the basin level and that the allo­ca­tion of its respon­si­bil­i­ties should pref­er­a­bly be con­fined to the extent of the river basin. The com­mon pur­pose of a basin man­age­ment insti­ tu­tion is to give effect to the prin­ci­ples of inte­grated water resource man­age­ment by assist­ing a national gov­ern­ment with the decen­ tral­ized man­age­ment of water resources in a cer­tain area of juris­ dic­tion. This means that the basin man­age­ment body must be rep­re­ sen­ta­tive of and facil­i­tate the involve­ment of the com­mu­ni­ties and other stake­hold­ers in deci­sion mak­ing about the water resources entrusted to the par­tic­u­lar body. A basin man­age­ment insti­tu­tion may have numer­ous respon­si­bil­i­ties, but one of the most impor­ tant is to advise the regional or national gov­ern­ment and to ensure that every­one has access to suf­fi­cient water of ­accept­able qual­ity;

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that the water resources are pro­tected against pol­lu­tion; that the water is used effi­ciently for the max­i­mum ­ben­e­fit of the pop­u­la­ tion and that envi­ron­men­tal sus­tain­abil­ity is not com­pro­mised in the pro­cess. The gen­eral under­stand­ing is that basin man­age­ment insti­tu­ tions are pri­mar­ily respon­si­ble for man­age­ment of water resources and other water related nat­u­ral resources on the sur­face in a geo­ graph­i­cal basin, but recent trends are that the man­age­ment of the “hid­den” water assets, the ground­wa­ter resources, should fea­ ture more prom­i­nently in the over­all strat­egy of inte­grated water resource man­age­ment. The pur­pose of this paper is to describe the practical imple­men­ta­tion of the con­cept of basin man­age­ment with ref­er­ence to the man­age­ment of ground­wa­ter resources through the estab­lish­ment and oper­a­tion of the Karst Water Man­ age­ment Body (KWMB) in Namibia.

2.2. Socio-eco­nomic impor­tance of the OML Due to the exis­tence of good qual­ity soils in the val­leys, excel­ lent range­land and that the mean annual rain­fall is about dou­ble what is received over the rest of Namibia, the area is suit­able for stock farm­ing and crop pro­duc­tion under dry­land con­di­tions or irri­ga­tion. The geol­ogy of the OML is also well known for its high base metal potential, mainly cop­per, lead, zinc, sil­ver and vana­ dium. A num­ber of mines and a cop­per smelter are in oper­a­tion. The main towns in the area are Tsumeb in the north, Ota­vi in the south­west and Groot­fon­tein in the south­east. These towns sup­port the local min­ing com­mu­nity and farm­ers within a radius of more than 100 km around each com­mer­cial cen­tre. The OML can rightly be regarded as one of the areas in the coun­try with sig­nif­i­cant eco­ nomic activ­i­ties, earn­ing for­eign exchange through the export of min­er­als and meat prod­ucts.

2. The Ota­vi Moun­tain Land 2.3. Hy­drog­e­ol­o­gy 2.1. Gen­eral back­ground The Ota­vi Moun­tain Land (OML) is a dolo­mitic mas­sif dom­i­ nated by a pro­nounced rug­ged relief, located in the north­ern part of the cen­tral high­land of Namibia (Fig. 1). The landscape rises to about 1090 metres (m) above mean sea level (AMSL) and some of the hills rise 500 m above the plains of the Kal­a­ha­ri fore­land. The OML cov­ers an area of approx­i­mately 25500 square kilo­me­ters (km2). The area receives an aver­age rain­fall of 540 mil­li­me­tres per annum (mm/a) in the north and this decreases to about 450 mm/a in the south. The potential evap­o­ra­tion var­ies from 2800 mm/a in the north to 3000 mm/a in the south. The OML rep­re­sents a watershed between the Eto­sha Depres­sion in the north­east, the Ugab River basin in the south­west and the Ok­av­an­go River basin on the east­ ern perim­e­ter, but there are no well defined, sur­face water drain­ age ­sys­tems. This absence of sur­face run­off is a very unique ­fea­ture of the OML and infers that most of the rain­fall infil­trates after pre­ cip­i­ta­tion or evap­o­rates (Christ­el­is and Struck­me­ier, 2001).

Geo­log­i­cally the OML con­sists mainly of quar­ter­na­ry Kal­a­ha­ri sed­i­ments and the rocks of the Da­mar­a Sequence. The sed­i­ments of the Kal­a­ha­ri Group cover about 56% of the OML and con­sist of cal­crete, do­lo­crete, cal­car­e­ous sand and gravel. The car­bon­ate and lime­stone rocks of the Ota­vi Group of the Da­mar­a Sequence cover about 23% of the OML and have been folded into a num­ber of anti­clines and syn­clines, gen­er­ally strik­ing east-west. The rest of the OML is cov­ered by the sand­stones and shale of the Mul­den Group, depos­ited in the val­leys formed by the syn­clines. The rocks of the Da­mar­a Sequence rest uncon­form­ably on the clas­tic and meta­mor­phic rocks of the No­sib Group while the gran­ites of the ­Groot­fon­tein Base­ment Com­plex are exposed in the south­east­ern part of the OML (DWA, 2002). The dolo­mite and lime­stone have little primary poros­ity, but the per­me­abil­ity of the rocks is locally enhanced due to intense frac­tur­ing and chem­i­cal weathering through the dis­so­lu­tion of the rock by rain­wa­ter. This is known as kars­tif­i­ca­tion and the OML is

Fig. 1. Loca­tion of the Ota­vi Moun­tain Land in Namibia.



P. Hey­ns / Physics and Chemistry of the Earth 33 (2008) 913–918

also known as the Karts Area due to the abun­dance of car­bon­ate rocks asso­ci­ated with these char­ac­ter­is­tic karst fea­tures. Two major aqui­fer types can be dis­tin­guished in the OML, namely the karst aqui­fers in the syn­clines and the Kal­a­ha­ri aqui­ fers. The karst aqui­fers host the most impor­tant ground­wa­ter resource in the region and the water is gen­er­ally of good qual­ity. The recharge to the aqui­fers is autoch­tho­nous or directly from rain­fall and the aqui­fers have a rel­a­tively large recharge potential due to the com­par­a­tively high rain­fall, the absence of soil cover in the moun­tains and the stor­age capac­ity in the kars­ti­fied dolo­mite syn­clines (DWA, 2002). These fea­tures facil­i­tate rapid infil­tra­tion dur­ing pre­cip­i­ta­tion and the pos­si­bil­ity to store large vol­umes of water in the aqui­fers. Although there is an absence of sur­face run­ off, there are numer­ous springs and a per­ceived abun­dance of shal­ low ground­wa­ter in the OML. The yield of some bore­holes in the karst aqui­fers can exceed 100 cubic metres per hour (m3/h) (DWA, 2002). The Kal­a­ha­ri aqui­fer is gen­er­ally con­sid­ered as a porous aqui­ fer, but in some places the aqui­fer may be com­pacted, frac­tured and locally kars­ti­fied due to the abun­dance of cal­crete and cal­car­e­ ous cement­ing. The thick­ness of the sed­i­ments increases from tens of metres along the perim­e­ter of the OLM to sev­eral hun­dreds of metres fur­ther away. The yield of the bore­holes drilled into the Kal­ a­ha­ri aqui­fers may vary between 5 and 30 m3/h. Due to the fluc­tu­a­tions in rain­fall and recharge to the aqui­ fers over time, the avail­abil­ity of water changes accord­ingly and through the mea­sure­ment of the water lev­els it was found that the water table con­tin­ued to drop as the demand increased (DWA, 2002). This is a mat­ter of con­cern, but it was also shown over time that good rain­fall events in the late sev­en­ties and the late nine­ties recharged the aqui­fers to a large extent. This meant that it was not so impor­tant to link abstrac­tion to recharge only, but that the stored vol­ume of water could also be uti­lized, thus cre­at­ing space in the aqui­fer that can be recharged dur­ing years with heavy rain­ fall. 2.4. Abstrac­tion con­trol After the dis­cov­ery of base met­als in 1915 and the devel­op­ment of mines, as well as the inter­est of the local stock farm­ing com­mu­ nity to irri­gate their dry­land crops when there is a lack of rain­fall, the water demand grew steadily and by 1970 the then Gov­ern­ment of Namibia became con­cerned that the uncon­trolled abstrac­tion of ground­wa­ter would be unsus­tain­able. Large vol­umes of water were being abstracted to dewa­ter the mines and some of this water was used for irri­ga­tion, which in turn stim­u­lated the inter­ est of more farm­ers to uti­lize the ground­wa­ter that occurred at shal­lower depths for irri­ga­tion. The regional nature of the water resources also had the impli­ca­tion that water users impacted upon each other and that gave rise to local con­flicts which were brought to the atten­tion of the Gov­ern­ment. It is well known that all water sources, includ­ing ground­wa­ter, are finite and have a lim­ited potential. The grow­ing water demand in the OML had to be man­aged, espe­cially in the absence of proper hy­dro­geo­log­i­cal inves­ti­ga­tions that could have deter­mined the potential of the karst aqui­fers at that time. It was there­fore decided to declare the OML a ground­wa­ter con­trol area. The Tsumeb–Ota­vi–Groot­fon­tein Sub­ter­ra­nean Water Con­trol Area, referred to as the Karst Water Con­trol Area (KWCA), was pro­claimed on 13 Novem­ber 1970 in terms of Sec­tion 28 of the Water Act of 1956 (DWA, 1956). The con­trol over and the use of the ground­wa­ ter was sub­se­quently pre­scribed in Reg­u­la­tion No. R1278, dated 12 July 1971. Accord­ing to the reg­u­la­tions any per­son who plans to sink, enlarge, deepen or alter any bore­hole or well or to open up or clean any spring or to abstract or use sub­ter­ra­nean water, shall apply for a per­mit (DWA, 1971).

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The main pur­pose was to col­lect infor­ma­tion and to pro­tect the water resources from over-abstrac­tion, but the reg­u­la­tions also pre­scribed mea­sures which made the rea­son­able and equi­ta­ ble allo­ca­tion of water to the dif­fer­ent users pos­si­ble through a “preliminary” per­mit sys­tem until the water resource potential could be inves­ti­gated more thor­oughly. Water that was abstracted for domes­tic use and stock water, as well as the irri­ga­tion of less than one hect­are of land was exempted from the per­mit require­ment because the quan­ti­ties of water were con­sid­ered to be rel­a­tively small. Any per­son or insti­ tu­tion that wanted to abstract water for com­mer­cial use had to make an appli­ca­tion in which a descrip­tion was required of the eco­nomic via­bil­ity of the par­tic­u­lar water use, as well as the quan­ tity of water required. This appli­ca­tion would be con­sid­ered in terms of other com­pet­ing uses and the potential of the aqui­fers to sus­tain the abstrac­tion of the quan­tity of water requested. A per­ mit was sub­se­quently allo­cated and the per­mit holder had to pro­ vide infor­ma­tion about the lithol­ogy of the bore­holes drilled, the quan­tity of water abstracted and the fluc­tu­a­tions in the water table, espe­cially before and after the rainy sea­son, in order to assist the ­Gov­ern­ment to deter­mine the behav­iour of the aqui­fers under oper­a­tional ­con­di­tions and to make some assess­ment of the potential of the aqui­fers. 2.5. National water trans­fers In 1974 the Gov­ern­ment announced a Water Mas­ter Plan for Namibia and one of the pro­posed water schemes was the devel­op­ ment of a water car­rier, known as the East­ern National Water Car­ rier (ENWC). The ENWC would link the ephem­eral sur­face water sources and ground­wa­ter sources in the inte­rior of the coun­try to each other and even­tu­ally with the Ok­av­an­go River to import peren­nial sur­face water to the arid cen­tral parts of the coun­try. This plan included the study of the potential of the ground­wa­ter resources in the OML and if the potential was ade­quate, to develop well-fields and con­struct pipe­lines to divert the water from the OML to other areas in the coun­try where there was devel­op­ment potential, but lack of suf­fi­cient water. The ENWC was grad­u­ally imple­mented in phases, but by 1987 the water car­rier reached the OML and the local com­mu­nity started to real­ize the real­i­ties of the pos­si­ble impacts of the Mas­ter Water Plan on their water resources. This was fur­ther com­pounded when the Gov­ern­ment started with fur­ther hy­dro­geo­log­i­cal inves­ti­ga­tions on pri­vate land to deter­mine the potential of the water resources. The farm­ing com­mu­nity was extremely con­cerned and objected to the use of their water in other areas in the coun­try where less water was avail­able. This issue was exac­er­bated by the fact that very little infor­ma­tion was avail­able about the potential of the aqui­ fers. The Gov­ern­ment was of the opin­ion that sur­plus water was avail­able for trans­fer pur­poses and the com­mu­nity felt that the water was not avail­able because the water table was already drop­ ping as a result of local use. It was clear that the need to inves­ti­gate the potential of the water sources became a pri­or­ity, but this could not be done with­out the sup­port of the farm­ing com­mu­nity who had to facil­i­tate the inves­ti­ga­tions on their land. 3. Estab­lish­ment of the Karst Water Man­age­ment Body (KWMB) Socio-eco­nomic devel­op­ment in the OML is based on min­ing, com­mer­cial agri­cul­ture and ser­vice indus­tries. The driv­ing force to sus­tain those activ­i­ties and to sup­ply water for domes­tic use, as well as to sup­port future devel­op­ments, is the avail­abil­ity of ground­ wa­ter. Per­ceived lim­ited ground­wa­ter resources, local com­pet­ing water uses and unwanted national inter­ests to trans­fer water out of the OML made the potential for con­flict very high. This could

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only be resolved by sci­en­tif­i­cally deter­min­ing the potential of the aqui­fer, build­ing trust and under­stand­ing, pro­mot­ing joint water plan­ning and to get the com­mu­nity involved in the sus­tain­able man­age­ment of the ground­wa­ter. This was essen­tial to main­tain the integ­rity of the resources, to allo­cate the avail­able water to the dif­fer­ent users in an equi­ta­ble and rea­son­able way and to use the water opti­mally and effi­ciently. In order to man­age the allo­ca­tion, abstrac­tion and mon­i­tor­ing of the aqui­fers in the OML, the Gov­ern­ment encour­aged the local water users to cre­ate a man­age­ment insti­tu­tion to assist the Gov­ern­ ment to man­age the aqui­fers in order to max­i­mize the ben­e­fits that can be obtained through the best joint uti­li­za­tion of the aqui­fers by all the water users. This led to the estab­lish­ment of the KWMB and is in line with the National Water Pol­icy (MAW­RD, 2000) and the Water Resources Man­age­ment Act, 2004 (Act 24 of 2004) which has not yet come into force. The stake­hold­ers in the OML drafted a Con­sti­tu­tion and the KWMB was prop­erly con­sti­tuted. The Gov­ern­ ment was requested to endorse and rec­og­nize the estab­lish­ment of the KWMB. This was sub­se­quently done because the KWMB was con­sid­ered to be a rep­re­sen­ta­tive body, and an excel­lent ini­tia­tive by the local stake­hold­ers and wor­thy of Gov­ern­ment sup­port. The main func­tions of the KWMB is to achieve max­i­mum ­secu­rity in the sup­ply of water to all the people in the Karst Water Con­trol Area (KWCA); to improve knowl­edge about the tech­ni­ cal, eco­nom­i­cal, envi­ron­men­tal, legal and admin­is­tra­tive aspects related to the water sec­tor in Namibia; to enhance com­mu­ni­ca­tion between the Gov­ern­ment; to con­sult with the insti­tu­tions engaged in pub­lic water ser­vices and the local water users in the KWCA; to develop a bet­ter under­stand­ing about water issues between all stake­hold­ers engaged in the water sec­tor in the KWCA and to ­pro­mote water aware­ness and stake­holder par­tic­i­pa­tion through reg­u­lar meet­ings between all the stake­hold­ers. The stake­hold­ers are rep­re­sented by a Coun­cil and an Exec­u­tive Com­mit­tee. The Coun­cil com­prises 15 mem­bers nom­i­nated by cer­ tain groups of stake­hold­ers, for exam­ple the regional gov­ern­ment, the local gov­er­nance insti­tu­tions at the three towns, the min­ing sec­tor, the farm­ing com­mu­nity, rep­re­sen­ta­tives from Gov­ern­ment Min­is­tries (who serve as advis­ors or observ­ers), non-Gov­ern­men­ tal insti­tu­tions, inde­pen­dent stake­holder groups and ex of­fi­cio mem­bers. The Exec­u­tive Com­mit­tee com­prises the Chair­per­son, the Vice-Chair­per­son and the Sec­re­tary. Other arrange­ments in the Con­sti­tu­tion cover such aspects as the elec­tion of office bear­ers, the vot­ing pro­ce­dures, the con­duct of meet­ings, a code of eth­ics and the pro­ce­dures to amend the con­sti­tu­tion. 4. Joint Man­age­ment of the KWCA 4.1. The rela­tion­ship between the KWMB and the Gov­ern­ment Fol­low­ing con­sul­ta­tions between the KWMB and the Depart­ ment of Water Affairs, a new pol­icy and strat­egy for the man­age­ ment of the KWCA and the allo­ca­tion of water abstrac­tion per­mits were agreed upon. The Gov­ern­ment will not with­draw any per­mit or allo­cate a new per­mit with­out con­sult­ing the KWMB. If the Gov­ ern­ment wants to take action against per­mit hold­ers who fail to com­ply with the per­mit con­di­tions, the KWMB will be informed. The Gov­ern­ment will mon­i­tor water lev­els and aqui­fer behav­iour in order to asses the annual avail­abil­ity of the water per­mit­ted for abstrac­tion and will inform the KWMB about the results as part of the capac­ity build­ing ini­tia­tive to empower the com­mu­nity to under­stand the man­age­ment and behav­iour of the aqui­fers bet­ter. 4.2. Man­age­ment prin­ci­ples The over­all man­age­ment of the ground­wa­ter in the KWCA stands on three pil­lars and is based on the inte­gra­tion of aqui­fer

man­age­ment, resource man­age­ment and water demand man­age­ ment. Aqui­fer man­age­ment relates to the sci­en­tific assess­ment of the potential of the aqui­fers, the allo­ca­tion of water and the mon­i­tor­ ing of the behav­iour of the aqui­fers under oper­a­tional con­di­tions. Resource man­age­ment refers to the appro­pri­ate man­age­ment of the aqui­fers and the envi­ron­ment through coop­er­a­tion between the users, the KWMB and the Gov­ern­ment. Water demand man­ age­ment refers to the respon­si­bil­ity of all water users to ensure loss con­trol and water use effi­ciency in order to make water avail­ able to as many irri­ga­tion farm­ers as pos­si­ble, thus max­i­miz­ing the socio-eco­nomic advan­ta­ges that can be obtained. 4.3. Water allo­ca­tion pri­or­i­ties The pri­or­i­ties for the allo­ca­tion of water were divided into primary, sec­ond­ary and ter­tiary con­sump­tion. Primary con­sump­ tion is water for domes­tic use in urban and rural areas, as well as for stock drink­ing on farms and in the rural areas. Sec­ond­ary con­ sump­tion is water for min­ing, man­u­fac­tur­ing and indus­tries. Ter­ tiary con­sump­tion is water for irri­ga­tion. The trans­fer of sur­plus water from the KWCA to other areas would only be allowed to meet primary and sec­ond­ary water demands. The prin­ci­ples for the award of per­mits to abstract water for irri­ga­tion require that the water must be allo­cated for the most ben­e­fi­cial and sus­tain­able uses; the quan­tity of water allo­cated should serve as an incen­tive to opti­mize irri­ga­tion meth­ods and water con­ser­va­tion; the avail­able water should facil­i­tate fur­ther agro-indus­trial and socio-eco­nomic devel­op­ment; the pro­cess of allo­ca­tion should be fair, open and trans­par­ent and that the stake­ hold­ers should be empow­ered to assist with the deci­sion mak­ing pro­cess to award the per­mits as well was to man­age the aqui­fers. 4.4. Deter­mi­na­tion of the sus­tain­able yield and ground­wa­ter avail­abil­ity The ini­tial pol­icy for the deter­mi­na­tion of the sus­tain­able yield or the avail­abil­ity of ground­wa­ter for allo­ca­tion was based on the lim­ited knowl­edge of the hy­dro­geo­log­i­cal envi­ron­ment of the karst aqui­fers, but as more stud­ies were done (DWA, 1990, 2002) and more infor­ma­tion became avail­able, the pol­icy was adjusted accord­ingly (DWA, 1992, 2004). The karst aqui­fers were ini­tially divided into five dif­fer­ent catch­ments accord­ing to the sur­face topog­ra­phy over each aqui­fer, rep­re­sented by a syn­cline, and for each catch­ment the per­mis­si­ ble abstrac­tion was derived from a con­ser­va­tive esti­mate of the annual recharge. The recharge of the aqui­fers was esti­mated at 2% of the mean annual rain­fall on the area under­lain by the car­bon­ate rocks. This was done by com­par­ing the drop in the water table due to abstrac­tion and rise in the water table due to rain­fall recharge. From this it can be deter­mined how much of the rain­fall over the aqui­fer will recharge the aqui­fer. The sus­tain­able yield or per­mis­si­ ble abstrac­tion was defined as equal to the recharge and based on these assump­tions it was esti­mated that the sus­tain­able safe yield of the aqui­fers is about 60 mil­lion cubic metres per annum (Mm3/ a). Each catch­ment was divided into 10 km £ 10 km blocks rep­re­ sent­ing 10,000 ha each. The per­mis­si­ble abstrac­tion for each catch­ ment was then divided by the num­ber of blocks in each catch­ment. The result­ing amount of water avail­able was divided by the unit quan­tity of irri­ga­tion water to deter­mine the num­ber of hect­ares that could be irri­gated in each block. The unit quan­tity of water for irri­ga­tion was deter­mined as 12,000 cubic metres per hect­are per annum (m3/ha/a). This is a con­ser­va­tive require­ment based on research done by the Depart­ment of Agri­cul­ture to deter­mine the water require­ments for irri­ga­tion under dif­fer­ent cli­matic and soil con­di­tions in Namibia and became gen­er­ally accepted practice. Per­mits were allo­cated in order of appli­ca­tion until the max­i­mum



P. Hey­ns / Physics and Chemistry of the Earth 33 (2008) 913–918

quota of water per block and per catch­ment were reached. This was done to pre­vent more abstrac­tion than the long term recharge in each catch­ment. Tra­di­tion­ally the safe yield of an aqui­fer is defined as the long term bal­ance between the amount of water abstracted and the amount of water recharged, but from the above it is clear that the safe yield had been deter­mined by tak­ing short term or annual recharge and abstrac­tion data into con­sid­er­ation. This con­cept was deemed inap­pro­pri­ate and not sus­tain­able after con­sul­ta­ tions between the farm­ers, agri­cul­tural experts and the Depart­ ment of Agri­cul­ture. The sus­tain­able safe yield should there­fore be deter­mined by tak­ing into account the out­flow of ground­wa­ ter from the aqui­fers, the impact of local or regional draw­down on the water table, the deple­tion or des­ic­ca­tion of springs, the effects of cli­mate vari­a­tions and change, as well as social, eco­ nomic and envi­ron­men­tal issues. This means that the sus­tain­able yield should be defined as the per­mis­si­ble abstrac­tion that would not allow the draw­down of the regional water table to lev­els below that which is accept­able with respect to both eco­nom­i­cal and envi­ron­men­tal con­cerns. A study to deter­mine the effect of a draw­down of the water table on the sur­face veg­e­ta­tion found that most of the veg­e­ta­tion has shal­low root sys­tems that do not draw water from the deeper lying aqui­fers. In other words, water that is not used has no eco­nomic value and should be used, but the level of impact on the envi­ron­ment would not be unac­cept­able. The pres­ent esti­mated sus­tain­able safe yield of the karst aqui­fers is about 36 Mm3/a. In order to achieve these objec­tives it is clear that the hy­dro­geo­ log­i­cal envi­ron­ment of the KWCA must be well under­stood, reli­ able data should be avail­able to esti­mate recharge accu­rately, the water stor­age char­ac­ter­is­tics of the aqui­fers should be under­stood, the impacts of a reduced water table on out­flows and the envi­ron­ ment should be stud­ied and an assess­ment of the risks of cli­mate change and sea­sonal rain­fall var­i­abil­ity should be done. Although the water allo­ca­tion pol­icy was deemed fair and ­rea­son­able at the time it was insti­tuted, a num­ber of improve­ ments were iden­ti­fied as more infor­ma­tion about the behav­iour of the aqui­fers under oper­a­tional con­di­tions became avail­able and the results of fur­ther ground­wa­ter stud­ies could be incor­po­rated. The com­mu­nity devel­oped a bet­ter under­stand­ing of the ground­ wa­ter sys­tems over time and could make use­ful con­tri­bu­tions to improve the admin­is­tra­tion and man­age­ment. The pres­ent sta­tus is that the karst area has been divided into eight regions and each region has been allo­cated a per­mit­ted long term sus­tain­able safe yield or a sus­tain­able quan­tity of water that could be allo­cated for irri­ga­tion. There are at pres­ent 89 per­mits issued that allow the use of about 11.3 Mm3/a for irri­ga­tion. Refer to Table 1 for an over­view of the allo­ca­tion of water in the KWCA. The issue of water trans­fer out of the KWCA was also inves­ti­ gated and it was found that in cer­tain high yield­ing areas it would be pos­si­ble to abstract about 36 mil­lion cubic metres (Mm3) of water at a rate of not more than 12 Mm3/a over a period of three years to meet short­falls else­where in the cen­tral area of Namibia. The aqui­fers should then be rested for up to 15 years to replen­ish

Table 1 Allo­ca­tion of water from the karst aqui­fers Con­sumer Group

Water allo­ca­tion (Mm3/a)

Urban domes­tic use Rural domes­tic use Min­ing and indus­trial use Irri­ga­tion use

4.4 4.8 12.3 11.3

Total

32.8

917

the water removed from stor­age. The KWMB and the Gov­ern­ment agreed on the pri­or­i­ties for such water trans­fers and the pos­si­bil­ity of future water trans­fers has been accepted. 4.5. Cri­te­ria for the allo­ca­tion of new per­mits Per­mis­sion to abstract addi­tional water for irri­ga­tion pur­poses will only be con­sid­ered if the allo­cated water quota for the area under con­sid­er­ation has not been reached. The unit quan­tity of irri­ga­tion water has been reduced to 10,000 m3/ha/a and will be applied when exist­ing per­mits expire and are renewed or when new per­mits are awarded. The renewal of exist­ing per­mits and the assess­ment of new per­mit appli­ca­tions will only be con­sid­ered once per annum in May and the awards will be made with effect from 1 July. The reason for this is the behav­iour of the aqui­fers after the pre­ced­ing rainy sea­son must first be assessed to con­firm the per­mis­si­ble quan­tity of water avail­able for allo­ca­tion. The max­i­mum valid­ity period of a per­mit is five years and the pur­pose of this is to ensure that the water that has been allo­cated is used. If the water is used for the intended pur­pose (mostly irri­ga­tion), the per­mit would be renewed, but if no irri­ga­tion devel­op­ment has taken place, the water will be allo­cated to other appli­cants. The reason for this is that some farm­ers applied for per­mits with­out any real inten­tion to invest cap­i­tal in an irri­ga­tion pro­ject, but just to be able to claim access to per­mit­ted water on his land and thus to improve the value of his land for spec­u­la­tion pur­poses. The max­ i­mum quota of water has also been reduced to 100,000 m3/a. This means that each appli­cant can get enough water to irri­gate 10 ha of land, pro­vid­ing the oppor­tu­nity to irri­gate more land by using more effi­cient irri­ga­tion tech­nol­ogy. This was also done to allo­cate water to more appli­cants and to spread the areas under irri­ga­tion more evenly through the karst area. Per­mit appli­ca­tions that have been rejected due to lim­ited water resources would be short listed for allo­ca­tion when per­mits are with­drawn from suc­cess­ful appli­ cants who failed to per­form. Per­mits will not be renewed or can be with­drawn if a per­mit holder fails to install the required water meters on the abstrac­tion equip­ment; fails to sub­mit the returns to the Gov­ern­ment for water abstracted water; exceeds the per­mit­ted abstrac­tion and does not use the water effi­ciently or does not use the water that had been allo­cated. 4.6. Pol­icy adjust­ments The deci­sion to set the sus­tain­able abstrac­tion of water from the karst aqui­fers equal to the recharge was changed because the approach did not make pro­vi­sion to accom­mo­date increased abstrac­tion by using the stored water reserves, which is in excess of 800 Mm3. The reduc­tion in through flow to down­stream areas was not accounted for and the low­er­ing of the water table due to the nat­u­ral out­flow of ground­wa­ter from the OML was not con­sid­ ered. These issues had to be brought into the equa­tion to deter­ mine aqui­fer behav­iour and the avail­abil­ity of water. The pol­icy to dis­trib­ute the per­mis­si­ble abstrac­tion evenly across the whole KWCA was recon­sid­ered because there were areas where the water could not be uti­lized due to the moun­tain­ ous nature of the land, or the lack of suit­able soils for irri­ga­tion, or when a farmer was just not inter­ested in irri­ga­tion. The “first come, first ser­vice” prin­ci­ple was also per­ceived as unfair by appli­ cants who had a late start with their deci­sions to start with irri­ ga­tion. The main reason for this was that many farms in the area received elec­tric­ity and it became more prof­it­able to irri­gate with water that could also be abstracted eco­nom­i­cally at greater depth. Pre­vi­ously the shal­low water was eco­nom­i­cal to use for irri­ga­tion in spite of using die­sel engines to drive the pumps, but when elec­ tric­ity became avail­able, those farm­ers also wanted to abstract

918

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more water at greater depths. This led to a gen­eral increase in the demand for more irri­ga­tion water. It was also expected by the com­mu­nity that the allo­ca­tion of water should be more trans­par­ent and that the Gov­ern­ment should solicit the views of the com­mu­nity before allo­cat­ing a per­ mit in order to avoid con­flict. The man­age­ment of the aqui­fers was com­pro­mised by users who abstracted more water than allo­cated, people who drilled bore­holes ille­gally and those who did not sub­ mit their abstrac­tion returns as required in terms of the per­mit con­di­tions. Many of these issues had a det­ri­men­tal effect on the avail­abil­ity of water for all the users and it soon became appar­ent that it was in the inter­est of all stake­hold­ers to get involved in the mon­i­tor­ing of those activ­i­ties as well and to report those that trans­ gressed the rules to the appro­pri­ate author­i­ties to enable them to take reme­dial action. This under­stand­ing between the par­ties enhanced coop­er­a­tion to the ben­e­fit of all. 5. Con­clu­sions The occur­rence, devel­op­ment and use of the ground­wa­ter resources in the OML as well as the ratio­nale behind the pro­cess to man­age water resources in a sus­tain­able way has be described to serve as an exam­ple for the man­age­ment of sim­i­lar ground­wa­ter resources in other coun­tries. The suc­cess­ful estab­lish­ment and oper­a­tion of the Karst Water Man­age­ment Body is based on the prin­ci­ple that the Gov­ern­ment wanted a coop­er­at­ing part­ner at the local com­mu­nity level to improve the sound man­age­ment of the karst area ground­wa­ter resources. At the begin­ning there was little local inter­est to par­tic­i­ pate, but when the Gov­ern­ment indi­cated its inten­tion to trans­fer water from the karst area to other areas in Namibia, the com­mu­ nity real­ized that there was a real threat to the secu­rity of their water sup­ply. The com­mu­nity started to orga­nize itself and to seek sup­port from the Gov­ern­ment to assist them to estab­lish a rep­re­ sen­ta­tive insti­tu­tion that could liaise com­pe­tently with the Gov­ern­ ment. In this way the Gov­ern­ment and the com­mu­nity man­aged to achieve their objec­tives because there is a via­ble part­ner­ship that can assist to improve the man­age­ment of the ground­wa­ter resources. The tech­ni­cal exper­tise vested in the Gov­ern­ment can now be applied to build the capac­ity of the Com­mu­nity to under­ stand how and why the water sources must be man­aged on a sus­ tain­able basis and why the water trans­fer plans would not impact adversely on their own access to ade­quate quan­ti­ties of water. In this way the per­ceived threats will be mit­i­gated and the secu­rity of sup­ply will be main­tained through the opti­mal man­age­ment of the water sources. Another lesson to be learnt here is that the imple­men­ta­tion of leg­is­la­tion is not the only driv­ing force to estab­lish water man­ age­ment bodies. When real needs or threats are evi­dent, it tends to rally people to orga­nize them­selves. There are of course other cases where the Gov­ern­ment has to take con­trol and there may then be a need to insti­tu­tion­al­ize water man­age­ment bodies, but the chal­lenge would be to get the coop­er­a­tion of the com­mu­ni­ties

with­out law enforce­ment and the feel­ing that the Gov­ern­ment is inter­fer­ing in issues at the local level. The objec­tive in such cases would there­fore be to con­vince the com­mu­nity that it is in their own inter­est to coop­er­ate and to par­tic­i­pate. This is also a ques­tion of edu­ca­tion and train­ing, or capac­ity build­ing, to empower the local people to under­stand the tech­ni­cal, social, eco­nomic and envi­ ron­men­tal issues at stake. At the time the KWCA was declared, the Gov­ern­ment was of the opin­ion that the potential exists for the over exploi­ta­tion of an impor­tant ground­wa­ter source and that abstrac­tion had to be con­trolled. It is nor­mally not pos­si­ble to man­age water resources prop­erly unless detailed hy­dro­geo­log­i­cal inves­ti­ga­tions have been done to deter­mine the potential of the ground­wa­ter resource. Ground­wa­ter inves­ti­ga­tions are very expen­sive and until such time an inves­ti­ga­tion is done, data can be col­lected that could be used to under­stand the behav­iour of the aqui­fer dur­ing recharge events and while water is abstracted. This infor­ma­tion will also be very use­ful when a for­mal hy­dro­geo­log­i­cal study is done. The best way to uti­lize the potential of an aqui­fer is to use it, but to mon­i­tor the behav­iour of the aqui­fer and that can be achieved by declar­ing the aqui­fer as water con­trol area with the objec­tive to con­trol abstrac­ tion and to col­lect data by mon­i­tor­ing water lev­els, rain­fall and the results of recharge events. By coop­er­at­ing in ground­wa­ter man­age­ment the KWMB and the Gov­ern­ment agreed on ground­wa­ter resource inves­ti­ga­tions, man­age­ment prin­ci­ples and prac­tices, water allo­ca­tion cri­te­ria, joint plan­ning, capac­ity build­ing and a pro­cess for reg­u­lar con­sul­ ta­tion, the exchange of tech­ni­cal infor­ma­tion and the build­ing of mutual trust. Ref­er­ences Christ­el­is, G., Struck­me­ier, W., 2001. Ground­wa­ter in Namibia: an expla­na­tion of the Hy­dro­geo­log­i­cal Map, Depart­ment of Water Affairs, Wind­hoek. DWA, 1956. The Water Act, 1956 (Act 54 of 1956) as made appli­ca­ble in South West Africa. DWA, 1971. Reg­u­la­tion No. R1278, dated 12 July 1971. DWA, 1990. An Eval­u­a­tion of the Ground­wa­ter Resources of the Groot­fon­tein Karst Area. Com­piled by the Geo­hy­drol­ogy Divi­sion, Depart­ment of Water Affairs, Min­is­try of Agri­cul­ture, Water and Rural Devel­op­ment, 1990. DWA, 1992. Cri­te­ria to be Con­sid­ered when Allo­cat­ing Per­mits for the Abstrac­tion of Ground­wa­ter for Irri­ga­tion Pur­poses in the Karst Area. Com­piled by the Geo­ hy­drol­ogy Divi­sion, Depart­ment of Water Affairs, Min­is­try of Agri­cul­ture, Water and Rural Devel­op­ment, Novem­ber 1992. DWA, 2002. Hy­dro­geo­log­i­cal Inves­ti­ga­tions to Deter­mine the Ground­wa­ter Potential of the Tsumeb Aqui­fers in Norh­ern Namibia (The Tsumeb Ground­ wa­ter Study). Com­piled by GKW Con­sult and Bicon Namibia, for the Depart­ ment of Water Affairs, Min­is­try of Agri­cul­ture, Water and Rural Devel­op­ment, Feb­ru­ary 2002. DWA, 2004. Revised Cri­te­ria to be Con­sid­ered when Allo­cat­ing Per­mits for the Abstrac­tion of Ground­wa­ter for Irri­ga­tion Pur­poses in the Tsumeb–Groot­fon­ tein–Ota­vi Sub­ter­ra­nean Ground­wa­ter Con­trol Area. Com­piled by the Geo­hy­ drol­ogy Divi­sion, Depart­ment of Water Affairs, Min­is­try of Agri­cul­ture, Water and Rural Devel­op­ment, June 2004. Global Water Part­ner­ship, 2000. Inte­grated Water Resources Man­age­ment. TAC Back­ground Papers No. 4. GWP Sec­re­tar­iat, Stock­holm. MAW­RD, 2000. National Water Pol­icy White Paper. Min­is­try of Agri­cul­ture, Water and Rural Devel­op­ment, August 2000. MAW­RD, 2004. Water Resources Man­age­ment Act, 2004 (Act 24 of 2004).