Management and evaluation of withdrawal ground water for agriculture in hamdan directorate-Yemen

Abstract

The aim of this research was to evaluate and determine ground water withdrawal for agriculture in hamdan directorate. The research was done by using random sample to measure and read the requirements data of agricultural hamdan wells. Associate professor, Agric. Eng. Depart., Fac. of Agric, Sana'a Univ. Yemen. abdallayaya87@yahoo.com Annual ground water withdrawals were compared with both of annual renewable ground water and actual crops water requirement in hamdan. Actual crops water requirements and irrigation scheduling, and quantity of water to be applied using surface and drip irrigation systems were done depending on data each of hamdan climate, crop coefficients and soil type by using a computer program (FAO). The results showed – as sample:- In hamdan directorate, the volume of annual groundwater recharge was found 3.341 MCM per year, while annual withdrawals volume of groundwater from all agricultural wells was found more than 99 MCM per year for irrigating only 5737ha. Thereby annual withdrawals of ground water was exceeded the renewable ground water by 29 times, So annual decrease of ground water level was found 3.4 m/year. About 90% of wells were not increased the distance among them on 500m. The distance average among wells in all directions was found 710m. The average of ground water amount for each hectare in hamdan was found more than 2.5 twice and twice of the actual water irrigation requirement for both of drip and surface irrigation systems respectively. So if drip irrigation system will be used in hamdan, it can be kept 47 MCM per year, which is now nearly 50% of withdrawal ground water. The time period of irrigation was found three times of calculated actual irrigation period average. Amount of irrigation water was found more with 7% and 38% than calculated actual amount average of irrigation water for each of surface irrigation and drip irrigation system respectively. The result was indicated that pump power was found excrescence on request (lost) with 54 KW/pump, so there was run-over power equal more than 900 pumps with power 43 KW, which can be provided from hamdan's pumps. Also, motor's power was found excrescence on request (lost) with 40 KW/motor, so there was run-over power equal more than 500 motors with power 58 KW. 42% of families in hamdan had been owned in agricultural well, while 58% of hamdan population (not own) could be used of agricultural wells.