Balancing abstraction and natural groundwater recharge as a mechanism of sustainable water use: a case study of the Kizinga catchment in Dar es Salaam region, Tanzania

摘要

This paper focuses on balancing groundwater recharge and abstraction rates as a mechanism of ensuring stainability of groundwater use. It uses a case study which was done in the Kizinga catchment area where its reacharge rates were evaklauted and then compared to that of abstraction. The study area is drained by river Kizinga having its upper reaches in Pugu and Kisarawe hills with a total surface area of 191 km~2. Determination of groundwater recharge rates gave a mean value of 52.8 mm/year which is equivalent to 10.1*10~6 m~3/year indicating that, 4.7% of the long term mean annual precipitation of 1124 mm ends up as groundwater reacharge. Borehole yields was 3.4*10~6 m~3/year by the year 1997. Two years later the total yield tripled to 9.1*10~6 m~3/year which is an increase of about 179% of groundwater production. Based on the study findings, it is therefore suggested that proposer management of groundwater utilization be established to balance feacharge with discharge. This will ensure that groundwater abstraction is done sustainably and thus avoid negative consequences resulting from groundwater depletion.