1 / 46

Integrated Water Resources Management Plan

Integrated Water Resources Management Plan. Dur Dur Watershed, Awadal Region, Somaliland. GROUNDWATER SURVEY (EA) Ltd. Water Resources Assessment Report. Introduction.

berny
Télécharger la présentation

Integrated Water Resources Management Plan

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Integrated Water Resources Management Plan Dur Dur Watershed, Awadal Region, Somaliland GROUNDWATER SURVEY (EA) Ltd

  2. Water Resources Assessment Report Introduction • IWRMP is designed to enable communities in the Dur-Dur Watershed to manage their NR and farming systems in a sustainable, efficient and equitable manner • Seeks to introduce soil and water conservation measures that will enable both crop farmers and livestock herders to improve their productivity • Target groups are: • the settled farming communities, • the transhumant agro-pastoral communities and • the trading groups that rely for their livelihoods on the natural resources of the Dur-Dur watershed. GROUNDWATER SURVEY (EA) Ltd

  3. Water Resources Assessment Report Introduction Cont. • Main Activities: • plan and implement comprehensive safe landuse and watershed management supported by cost effective soil and water conservation infrastructure, • a sustainable range management framework • introduction of sustainable low input, high output agricultural production • the development of local institutions, linked to Regional Governmental structures to monitor and enforce national policy and practice on natural resource management at a local level. GROUNDWATER SURVEY (EA) Ltd

  4. Water Resources Assessment Report Location Map of Study Area GROUNDWATER SURVEY (EA) Ltd

  5. Water Resources Assessment Report Scope of Work and Objectives • Desk study and review of relevant data • Participation of the local community in all steps of plan development • Comprehensive assessment of the water resources • Comprehensive assessment of climate data • Evaluation of combined water demand • Participation of stakeholders and line ministries • Data processing with Geographic Information Systems (GIS) • Linkage to the FAO Water and Land Information Management Project. • Environmental aspects of further water development in the area • Analysis of investment costs. GROUNDWATER SURVEY (EA) Ltd

  6. Progress to Date • Reconnaissance Study and Preparation of Inception Report (25.02.05-25.03.05) • Detailed Field Investigation for Water Resources Assessment in Project Area (25.03.05-02.05.05) • Participatory Workshops in Borama and Baki with stake holders (July 2005). • Preparation of IWRMP draft reports and Water Resources Assessment Reports (Aug ’05- Dec 05) • Presentation of Draft Reports to GAA (Dec 05). GROUNDWATER SURVEY (EA) Ltd

  7. Water Resources Assessment Report Approach by the Consultant • Study subdivided into two Phases: Phase I: Water Resources Assessment Study Phase II: Water Resources Planning, Landuse Analysis, Soil and water Conservation. • Water Resources Study (Phase I) • comprehensive desk study and data-acquisition phase • reconnaissance survey, preparation of inception report • Field inspection and condition assessment of existing groundwater and surface water facilities • Geological, hydrological, hydrogeological and geophysical investigations: Analysis of geophysical data. • Selection of sites for exploratory drilling where appropriate • Data Analysis • Preparation of Water Resources Assessment Draft Report GROUNDWATER SURVEY (EA) Ltd

  8. Water Resources Assessment Report Geology of Dur Dur Watershed • Basement Rocks: Xirsi Jiciir, Fooda, Borama, Bown (Upper Catchment); East of Hamarta and north of Horey (Middle Catchment). In the lower part of Dur Dur Catchment, basement rocks outcrop in Waragadhita, Sheaar Dheeer and Karinkari areas. • Jurassic Sediments: east & north east of Borama, of which the best described are Dhamuuq, and the Dibrawein Valley between Ceel Berdale and Ruqi • Pleistocene Volcanics: Aden volcanics, cap the peaks of the mountainous parts of the middle part of the Dur Dur Catchment. • Montane Alluvial Deposits: Alluvium, at least 95m thick, overlies Jurassic limestones in the Dibrawein Valley & Dhamuuq valley • Coastal Plain Alluvial Deposits: Balley valley, Gabaraho, Gargara and Lughaya areas. GROUNDWATER SURVEY (EA) Ltd

  9. Water Resources Assessment Report Geological Map of Dur Dur Catchment GROUNDWATER SURVEY (EA) Ltd

  10. Water Resources Assessment Report Hydrology of the Catchment • Floods are short but violent • Large amount of river water is lost by heavy infiltration in the sandy riverbeds & evaporation of water retained in the soils • The Durdur drains a catchment area over 4185 km2 with a mean rainfall of 342 m • Upstream section receives 500 mm of rainfall • In rainy season in different parts of the Dur Dur catchment, not all the flush floods reach the Gulf of Aden, some are infiltrated in the sands and sandy clay deposits to contribute towards the groundwater recharge in the lower catchment • Upstream of Qabri Baxar the yearly runoff is 160 Mm3 • Only 35 to 40 Mm3 appears as surface water at Qabri Baxar • 125 Mm3 of water is absorbed into the numerous togga beds, which drain the catchment area GROUNDWATER SURVEY (EA) Ltd

  11. Water Resources Assessment Report Hydrogeology of the Catchment The aquifers in the Dur Dur Catchment can be classified into four main categories dependent on their geological characteristics: • Jurassic Sediment Aquifers (Limestones which cover most of the Dibra Weyn – Bown Axis • Basement aquifers • Montane Alluvial aquifers (which occur mainly in the toggas within the Catchment) • Coastal Plain Alluvial Aquifers – Garbaraho and Gargara Area GROUNDWATER SURVEY (EA) Ltd

  12. Water Resources Assessment Report Groundwater Recharge Three types in study area: • Direct recharge. recharge directly from infiltrating rain into an aquifer unit. • Indirect or allogenic recharge; recharge from rivers or streams • Lateral recharge from one geological unit to another at depth GROUNDWATER SURVEY (EA) Ltd

  13. Water Resources Assessment Report Water Quality • The primary water quality problems are bacterial contamination and high total dissolved. Solids (TDS), primarily sodium, chloride and sulphate. • Bacterial contamination is caused by poor, or many times, non-existent protection measures near water supplies. The proper installation of wells and pumping facilities can eliminate this problem in most cases. • Excessive TDS is due to: • The concentration of dissolved solids by high evaporation rate • The leaching of salts from Cretaceous and younger marine sedimentary rocks GROUNDWATER SURVEY (EA) Ltd

  14. Water Resources Assessment Report Research Findings • Upper Catchment- Limited Groundwater Potential • Basement rocks have poor permeability and storage capacity • Upper part receives minimal recharge from rainfall, most runoff flows downstream • Potential groundwater situated mainly in limestone terrains • Middle Catchment- Moderate Groundwater Potential • Sustainable groundwater resources from shallow wells and springs • Good alluvial deposits in vicinity of toggas • Presence of fractured limestones • High yielding springs • Some areas with highly weathered limestone have low yields due to formation of clay • Lower Catchment- Very High Groundwater Potential • Receives most recharge from flush floods • Has thick alluvial deposits formed of sands and sandy clays which are good for water storage • Boundary between limestones and basement rocks form sources of high yielding springs GROUNDWATER SURVEY (EA) Ltd

  15. Water Resources Assessment Report Borama Condition Assessment: • 8 existing boreholes- WRL dropped from 8.08m.bgl. (in 1986) to 23.91m by January 2005. Implies 15.83m drop in nearly 20 years • Irrigation farming activities not viable in Borama town given the limited water resource • Proper test pumping exercise for the 8 boreholes to determine the exact safe yield which will not cause further aquifer depletion. • Need for alternative sources for urban water supply to cater for both current and future demand. • The communities should invest in alternative sources such as rainwater harvesting, subsurface dams, ponds and roof catchment. GROUNDWATER SURVEY (EA) Ltd

  16. Water Resources Assessment Report Borama-Cont. Geophysical Investigations: • Control soundings on existing BHs • Only BH one site recommended for drilling • Need for detailed investigations for alternative water supply for the town Water Demand: Domestic: 6000m3/day(by 2015) NB:SHABA is currently has a maximum production capacity of 35,786m3/month = 1192.86m3/day.Future demand for the town stands at 6000m3/day (i.e. the company will be supplying only 19.88% of required demand )

  17. Water Resources Assessment Report Location Map of Existing & Potential Sources in Borama GROUNDWATER SURVEY (EA) Ltd

  18. Water Resources Assessment Report Dilla Condition Assessment: • One Borehole at the town with discharge of 2m3/hr. • Dilla area described as unfavourable for groundwater development • over 3000 rainfed farms in the area • the berkards (10 in number) that were constructed in the area were destroyed • the Consultant team encountered only two functional berkards within the vicinity of the town that are privately owned • community is keen on restoration of soil erosion systems in the area as well as construction of dams which could last up to six month a year after wet season. GROUNDWATER SURVEY (EA) Ltd

  19. Water Resources Assessment Report Halimale Condition Assessment: • Halimale has most of its shallow wells located along the Halimale Togga • Shallow wells in Halimale area have good potential along the togga • However, as you approach towards the north west, water table becomes deeper and the groundwater potential also becomes limited Geophysical Investigations: • Six VESs were executed at hydrogeologically conducive locations at the expanse • Development of shallow groundwater is possible near the toggas • General formations that exist in the area show conditions that does facilitate development of shallow aquifers GROUNDWATER SURVEY (EA) Ltd

  20. Water Resources Assessment Report Location map for Halimale GROUNDWATER SURVEY (EA) Ltd

  21. Water Resources Assessment Report Bown Condition Assessment: • One subsurface dam in Bown area constructed by IFAD along the Togga Abassa • No signs of shallow wells within the vicinity of Bown area • Attempts by the community to dig shallow wells in area have always been futile due to the presence of very heavy clays along togga Abassa • Not advisable to provide water for irrigation activities in Bown area Geophysical Investigations • A profile of 420 m long and 3 VESs were executed at hydrogeologically conducive locations • development of shallow groundwater is not a viable option in this area • However, at least three sites were recommended in Bown area GROUNDWATER SURVEY (EA) Ltd

  22. Water Resources Assessment Report Location Map for Bown Area GROUNDWATER SURVEY (EA) Ltd

  23. Water Resources Assessment Report Baki Condition Assessment: • Baki area has over 78 shallow wells although the number keeps increasing. • Some shallow wells are unlined & do not have well head - poses a great risk of contamination as well as accidents to both children and even livestock • Daily discharge from these shallow wells stands at an estimated figure of 67m3/day • GAA has supplied the farmers in Baki area with pumps • The village has an irrigable area of about 609(ha). • Installation of monitoring well recommended. Geophysical Investigations: • 23 VESs were conducted - groundwater development for deep aquifer is unfavourable in Baki area. • Hydrogeologically, “Baki Basin” is covered by clay and sandy clay deposition from both Dibra Weyn Valley and Bira togga • Further investigations revealed that the shallow aquifers along the toggas were a result of sand deposition whereas deep aquifers are not feasible close to the toggas due to deposition of the heavy clays • This implies that farms away from the toggas will not benefit from the prevalent 5 – 10 m deep shallow wells • Deep aquifers- clay formation prevalent • 13 recommended drilling sites in Baki area GROUNDWATER SURVEY (EA) Ltd

  24. Water Resources Assessment Report Location Map for Baki GROUNDWATER SURVEY (EA) Ltd

  25. Water Resources Assessment Report Ruqi Condition Assessment: • Over 37 shallow wells located along Dibrawein togga. • Most of water for irrigation faming is supplied by Ruqi spring (191m3/hr) • Daily average discharge in Ruqi valley = 204m3/day. • About 61% of the wells have unconfined aquifers while the rest are confined. • 86% of the shallow wells have good quality water especially those located close to the Dibrawein togga. • Village has two canals constructed by CARE - total length of 7600m • The canal discharges at least 10 L/s. • Ruqi village has about 142 farms which are irrigated • The number of rainfed farm in the area stands at 130 GROUNDWATER SURVEY (K) Ltd GROUNDWATER SURVEY (EA) Ltd

  26. Water Resources Assessment Report Ruqi Cont. Geophysical Investigations: • 5 profiles of 2.22 km long and 21 VESs were executed • Development of shallow groundwater is possible along the Dibra Weyn togga and within the fractured limestone • Thick clay formation was noted in some areas.. • Away from the togga especially towards Alog Mountains investigations do not indicate the presence of clays • Upstream and Downstream of Ruqi alluvial series with thickness of at least 100m have accumulated. GROUNDWATER SURVEY (EA) Ltd

  27. Water Resources Assessment Report Location Map for Ruqi GROUNDWATER SURVEY (EA) Ltd

  28. Water Resources Assessment Report Heego Condition Assessment: • Heego village has 11 shallow wells • Daily average discharge stands at about 19.2m3/day • However there are two canal systems in Daraso farming area • The village has only 41 farm areas • The number of rainfed farms is approximated at 108 Geophysical Investigations • A profile of 400 m long and 10 VESs executed • Development of shallow groundwater is possible along the toggas and within the fractured basement and limestone rocks • Further away from the toggas, pockets of the thick clay formation exist and lack of recharge does not facilitate development of shallow aquifers. GROUNDWATER SURVEY (K) Ltd GROUNDWATER SURVEY (EA) Ltd

  29. Water Resources Assessment Report Location Map for Heego Area GROUNDWATER SURVEY (EA) Ltd

  30. Water Resources Assessment Report Adaad Condition Assessment: • Adaad has over 25 shallow wells mainly along Togga Abassa and Togga Bedenbed • Average water rest level of 3.3mbgl • There are two springs in Adaad area namely Nadhi and Xidigale all located within the limestone formations • The area has at least 3000m of canal Geophysical Investigations: • A profile of 600 m long and 11 VESs were executed at hydrogeologically conducive locations. • Thick clay formation is not a big problem at the investigated sites of Adaad. • However the major challenge was that in Adaad centre some VESs which had good indication for groundwater potential were not located at areas where neither fractured limestones nor Basement rocks could get sufficient recharge. • Locations for productive shallow wells are rare and this puts development for shallow groundwater difficult even near toggas GROUNDWATER SURVEY (EA) Ltd

  31. Water Resources Assessment Report Location Map for Adaad Centre GROUNDWATER SURVEY (EA) Ltd

  32. Hamarta Condition Assessment: • 2 springs namely El Gorey and Andhoubeyd located in the limestones • Has highest number of canals in the middle catchment (at least 9) covering total length of 9,000m • Average discharge of these canals is approximately 15L/s. • Andhorey spring (151 m3/hr) , El Gorey Spring (227.908m3/hr). Geophysical Investigations • A profile of 340 m long and 5 VESs executed • From the geophysical models thick clay formations are rare. • Development of shallow groundwater is possible along the toggas. • Away from the toggas, the area is surrounded by limestone hills which might not form good aquifers due to lack of recharge. GROUNDWATER SURVEY (EA) Ltd

  33. Water Resources Assessment Report Location Map for Hamarta GROUNDWATER SURVEY (EA) Ltd

  34. Horey Condition Assessment: • Has three Springs (Dhambi, Goldfadhi, & Byihumo). • The village has over 7 canals length of 9600m • The average discharge capacity is approximately 25 l/s • There are about 79ha of active irrigation areas in Horey while over 248 ha still lie fallow. • Horey spring has an approximate discharge of about 134.395m3/hr. Geophysical Investigations: • Their main source of water is a spring • A profile of 1.76 km long and 8 VESs were executed at locations of hydrogeological interest. • From the interpretation of geophysical data for the area, suitable points where productive shallow wells can be located are rare • Thick clay formation is however not a big problem at the investigated sites of Horey. GROUNDWATER SURVEY (EA) Ltd

  35. Water Resources Assessment Report Location Map for Horey GROUNDWATER SURVEY (K) Ltd GROUNDWATER SURVEY (K) Ltd GROUNDWATER SURVEY (EA) Ltd

  36. Water Resources Assessment Report Old Baki Condition Assessment: • Old Baki has at least 20 active farming areas • There are at least 77 rainfed farms in the area. • The only permanent water sources in the village are shallow wells located at Qotonxarshe, Dhabacdhabac, Watan, Dhabi and Sagalay • Most of the shallow wells in Old Baki have very limited potential. Geophysical Investigations: • 2 profiles of 680 m long and 11 VESs executed • Thick clay formations are rare in this area. • Development of shallow groundwater is possible along the toggas although locations with suitable storage conditions need to be assessed first • Further away from the toggas, the formations that exist in the area lack enough recharge and this does not facilitate development of shallow aquifers. GROUNDWATER SURVEY (EA) Ltd

  37. Water Resources Assessment Report Location Map for Old Baki GROUNDWATER SURVEY (EA) Ltd

  38. Water Resources Assessment Report Garbaraho Condition Assessment: • Garbaraho farm area has several shallow wells with an average depth of 8m along the Durdur togga. • The shallow wells have been supplied with pumps from DRC which is the intervention agency in the area • There are several springs emanating from the junction between the Gobdheere togga and Dur Dur Togga • The limestone series is highly fractured and karstified thus acts as a good aquifer for groundwater storage • Estimated discharge from the springs is over 416.3m3/hr. The springs serve both Balley valley and Turka areas. GROUNDWATER SURVEY (EA) Ltd

  39. Water Resources Assessment Report Garbaraho Cont. Geophysical Investigations: • The active farms are irrigated from shallow wells and springs • A 740 m long profile and 10 VESs were executed at hydrogeologically conducive locations at Gobdheere and Qudhaanjaley area • Interpretation of geophysical data and the assessment of the shallow wells in the area show that development of shallow groundwater is possible near the toggas • The formations that exist in the area show conditions that does facilitate development of shallow aquifers • In Garbaraho area there mainly two aquifers which belong to the brown and red sandy clay alluvium and the clayey sand alluvium of the togga. These aquifers were confirmed by SOGREAH during the drilling campaign. They are formed of alluvium laid down during several cycles • Five sites were selected as potential for development of deep boreholes. GROUNDWATER SURVEY (EA) Ltd

  40. Gargara Condition Assessment: • 3 boreholes which were drilled by the SOGREAH in 1982. • The boreholes were drilled for exploratory purposes but was not installed with a submersible or a hand pump. • One has a total depth of the borehole is 88m with an estimated discharge of 3000m3/day • The borehole was destroyed by flush floods and unfortunately it can not be rehabilitated. • Replacement borehole at this location is not advisable because it will still be damaged by the flush floods GROUNDWATER SURVEY (EA) Ltd

  41. Gargara Cont. • Geophysical surveys targeting the active and potential farm areas at Turka, Balley and Hulhudhuunle villages were carried out to establish the groundwater potential. • Three profiles of 2.1 km long and 12 VESs were executed at hydrogeologically conducive locations at areas in Hulhudhuunle, Turka and Balley villages • From the geophysical models, thick clay formations are rare although saline clay formation is common in Balley area. • Two sites each at Balley and Turka, and three sites at Hulhudhuunle were selected as potential for development of deep boreholes GROUNDWATER SURVEY (EA) Ltd

  42. Water Resources Assessment Report Location Map for Garbaraho GROUNDWATER SURVEY (K) Ltd GROUNDWATER SURVEY (EA) Ltd

  43. Water Resources Assessment Report Location Map for Gargara GROUNDWATER SURVEY (EA) Ltd

  44. Water Resources Assessment Report Location Map for Turka GROUNDWATER SURVEY (EA) Ltd

  45. Water Resources Assessment Report Conclusions • Good Groundwater potential in the Dur Dur Catchment has been established in the Middle and the Lower Catchment of the watershed. • Condition Assessment has revealed that there are less water resources in the Upper Catchment and therefore the communities will have to seek for alternative water sources to supplement the existing sources. • It is also apparent that it may not be possible to carry out irrigation activities in most part of the upper catchment due to the limited water resources especially in Borama town. • The existing water sources in the middle catchment and lower need proper environmental protection measures such as well lining, well head protection and fencing off a protection perimeter for the sources • Abundant groundwater sources have been established mainly in the limestone series which receive recharge from inflow from surface water infiltration • Mean annual yield in the Dur Dur Catchment has been estimated to be 34 M3 in the lower part of the Catchment. GROUNDWATER SURVEY (EA) Ltd

  46. Water Resources Assessment Report Recommendations • A comprehensive test pumping programme is carried out in the production boreholes that have not been tested properly in Borama Area to establish the safe yield of the well field. • Consider & investigate alternative potential large scale surface water storage (Dams) • One environmental monitoring well should be installed in Baki area to monitor changes in the middle catchment caused by ever increasing number of shallow wells for irrigation activities and also the water quality. • Installation of piezometer tubes for water level monitoring as well as flow meters is done in all the production boreholes that would be drilled in the Lower Catchment is very essential. This will enable accurate recording of the abstraction as well the drawdown at any time. • A monitoring programme lasting not less than one year is instituted to monitor the water level in response to pumping in order to determine the catchment capability and the safe yield. This will entail recording of the water levels on a daily basis in the observation wells as well as the production boreholes GROUNDWATER SURVEY (EA) Ltd

More Related