Shahid Ahmad

Reducing water seepage from earthen ponds

Abstract Small earthen reservoirs have proved to be a promising answer to the problem of storing water on arid-land farms. However, these little ponds or tanks can lose very large amounts of water through seepage. To reduce such losses is a vital need. In the present experiments, chemical, physical, and biological methods for reducing seepage were evaluated in small ponds created in a permeable, calcareous, silt-loam soil. The chemical method involved treating the top 10 cm of soil with sodium carbonate (Na2CO3). The physical method involved compacting the soil. And the biological method (the so-called “bio-plastic sandwich”) consisted of successive layers of soil, manure, vegetative material and soil. The chemical treatment proved less efficient than the other two. Compared to the untreated soil, the physical and biological methods reduced the mean cumulative seepage rates (measured 350 days after the initial wetting) by 72% and 67%, respectively. Both of these treatments seem to be cost-effective and ready to be applied to the farm ponds of Pakistan.

Flow measurements with portable cut-throat flume and broad crested weir in flat gradient channels

A study was conducted to evaluate the reliability of flow measurements with portable cut-throat flumes and broad-crested weirs during 1988–89 at the field hydraulic laboratory of the National Agricultural Research Centre, Islamabad. Data of flow measurements were recorded under free and submerged flow conditions with a cut-throat flume and a broad-crested weir as compared to a standard ‘V’ notch. The results indicated that for free flow conditions cut-throat flumes can be used with –2.2 to 8.6% error. However, the use of cut-throat flumes under flat gradient channels may cause problem of over-topping at the upstream end. Under submerged flow conditions, the percent error in the flow measurements of −3.2 to 14.6% was observed. Therefore, cut-throat flumes cannot provide reasonable flow measurements under submerged flow conditions. For accurate flow measurements broad-crested weirs should be used with percent error of −1.5 to 5.8. Such flumes can be easily manufactured in Pakistan to suit different flow regimes and flat gradient channels.

Computerized scheduling for irrigation management and pumping operations in the watercourse command

Abstract A model to simulate the irrigation schedules of a watercourse command was developed to predict cropping intensity, net farm return, farm water use, percent water utilized, deep percolation at farm level, rainfall contribution, and extra tubewell water pumped. Schedules for three selected farms on a watercourse command in Sargodha, Pakistan were simulated with three fixed-rotation strategies and compared to a demand strategy. The fixed-rotation strategies were also compared for evaluation of the allowable depletion criteria. Evaluation of simulations (1973–1982) showed that the three fixed-rotation strategies reduced the net farm return by 28–43% from that of a demand strategy. The fixed-rotation system also had 17–39% of extra water pumped from a public tubewell. Therefore, when the existing operation schedules of the tubewells are matched with the actual crop water needs an ultimate saving of 17–39% in water pumpage and energy consumed will be reached in a fixed-rotation system. The change of the fixed-rotation system to a demand system will significantly increase the net farm return in addition to improved water allocation to various farms on a watercourse command. The demand strategy will provide saving in energy due to scheduled pumping operations and effective utilization of canal water supplies.

Distribution of Wild Mammalian Fauna of Mahaban and Malka Valley District Buner

Naveed Akhtar,1,* Riaz Muhammad2, Kausar Saeed2, Muhammad Fiaz Khan1, Muzaffar Shah3, Jehan Zeb2, Shahid Ahmad2, Azam Jan Afridi4 and Aftab Hussain5 1Department of Zoology, Hazara University, Mansehra 2Department of Zoology, Abdul Wali Khan University, Mardan 3Center for animal sciences and fisheries, University of Swat, Swat 4Department of Zoology Islamia College University, Peshawar 5Department of Genetics, Hazara University, Mansehra Article Information Received 15 December 2016 Revised 03 March 2017 Accepted 01 April 2017 Available online 15 March 2018

HYDRAULIC PERFORMANCE OF RAINGUN SPRINKLER IRRIGATION SYSTEM USING LOW CAPACITY DUGWELL

This research work was carried out at Phularwan Research Farm of the Mona Reclamation Experimental Project, WAPDA, at Tehsil Bhalwal of Sargodha district. Raingun (PY,-30) was operated with 12-mm and 10-mm nozzle sizes. Water source was a dugwell whose recharge rate was very less. Thus steady state could not be obtained as the discharge exceeded the recharge rate during pumping. The effect of continuous fall of water level in the dugwell on the performance of raingun sprinkler irrigation system was evaluated. Relationships were developed between various parameters affecting the performance of the system. Discharge, pressure and radius of raingun throw decreased with the fall of water level in the dugwell. These variations in the values of various parameters adversely affected the application rate and water distribution uniformity of the raingun sprinkler irrigation system. The reduction in size of nozzle with the fall of water level in the dugwell has caused some improvements. The coefficient of uniformity values increased toward the center of the wetted area. The hydraulic gradient was found very steep near the dugwell, which has reduced the radius of influence of the dugwell. The reason for slow recharge rate was found to be the clogged screen section of the dugwell as it had been abandoned for more than thirty years and tight brick lining having no perforations. Application rate increased with time ofpumping as the wetted area decreased due to reduction in radius of raingun throw.

EVALUATION OF RAINGUN (PY-30) WITH 10 MM DIAMETER NOZZLE

The raingun ( PY -30) with 10 mm diameter nozzle was operated under 13 different pressures ranging from 20 to 80 psi with an interval of 5 psi. Each set of data was replicated thrice. The water application rate, distribution pattern, discharge and radius of coverage were measured with pressure. The coefficients of uniformity of the raingun were determined in four quarter by dividing the radius of coverage into four equal parts and at effective radius of coverage. The values of coefficient of uniformity were higher ( 95.85% ) in the first quarter and lower (48.03%) in the fourth quarter. The discharge of the raingun was 21.40 gpm at 20 psi pressure and 39.31 gpm at 80 psi pressure. The discharge increased with the increase in pressure. The radius of coverage was found to be 20.5 m at 20 psi pressure and 24.5 m at 80 psi pressure. The radius of coverage increased with the increase in pressure but the increase in radius of coverage was not uniform and regular. The application rates of the raingum under various pressures were determined. The maximum application rate of 4.73 mm/hr was found at 80 psi pressure and the minimum application rate of 3.51 mm/hr was found at 30 psi pressure. A strong relationship was obtained between pressure and application rate.

WATERCOURSE CONVEYANCE EFFICIENCY AND WATER AVAILABILITY ON A WATERCOURSE COMMAND

Watercourse conveyance efficiency and water availability was estimated on a watercourse command of SCARP Tubewell # 56L and canal outlet (mogha ) # 62394L at BhalwalSargodha. The selected watercourse command comprised of 401.3 ha of command area and 41 farms. The loss rate of 1.46% per 100 m length of channel was used as constant loss rate function for the analysis of conveyance losses. The mean conveyance efficiency at square inlet of watercourse command of 70% was observed. The average conveyance efficiency at field gate was about 67.8% over the selected watercourse command. The average actual water availability was 83.6, 64.7 and 54.0% of the water allocation at the head, the middle, and the tail farms, respectively.The total length of the main watercourse was about 9.0 kilometers, whereas, the total length of the branch watercourses was about 30 kilometers.The main watercourse contributed 93% of the total conveyance losses because main watercourse was in operation for 100% time of each turn. The field watercourses were in operation of about 4.3 hours per week per square of the selected command.

SPATIAL VARIABILITY IN SEASONAL CROP EVAPOTRANSPIRATION AND MOISTURE STRESS FUNCTIONS

The seasonal crop evapotranspiration (Et ) for wheat, cotton and sugarcane crops was used to estimate variability in seasonal Et and potential yield for major climatic zones. The average seasonal crop Et varied between 353-562, 587-797 and 1195-1482 mm for wheat, cotton and sugarcane crops, respectively, for major climatic zones. The variability in seasonal crop Et for various locations was highly significant for wheat and cotton and nonsignificant for sugarcane. Same trend was observed for potential yield. Seasonal crop Et - moisture stress functions were developed for wheat and cotton crops representing 50, 75 and 95% soil moisture depletion. Average water use efficiency for wheat and cotton crops is presented for number of locations. Water use efficiency was increased with the increase in soil moisture stress as irrigation timing criteria of 75 and 95% from that of 50%. Crop coefficients for wheat and sugarcane were affected by moisture stress especially during the peak water requirement period. This indicates the need to adjust crop coefficient with moisture stress because actual crop Et is reduced with the increase in soil moisture stress.

Irrigation scheduling and water availability at watercourse command

A model that simulated the irrigation schedules of a farm at watercourse command was developed to predict net farm return, benefit-cost ratio, water use, percent water utilized, deep percolation, rainfall contribution and net return per unit of water applied including rainfall. Schedules for three selected farms on a watercourse command of Tw #62394L from MONA, Sargodha, Pakistan were simulated with 3 fixed-rotation and 2 demand strategies to evaluate the allowable soil water depletion criteria. Evaluation of the simulations (1973–82) showed that the water availability reduced the net farm return of 15 and 31% at the middle and tail farms, respectively, from that of the head farm. Therefore, the existing water allocation procedure (WARABANDI) should include watercourse conveyance losses to provide equitable water distribution on a watercourse command. Demand water availability can increase the net farm return of 25 and 26% in strategies 4 and 5, respectively, by changing the fixed-rotation system to a demand system. Changing the fixed-rotation system to a demand system requires either the use of existing private tubewells or the installation of new private tubewells.