Assessment of climate change impact on irrigation water demands and rainwater harvesting for drip-irrigated high value crops in Pothohar, Pakistan | |
| Author | Hussain, Zahid |
| Call Number | AIT Thesis no.WM-18-24 |
| Subject(s) | Climatic change--Pakistan Irrigation water--Pakistan Rain-water (Water-supply)--Pakistan |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Water Engineering and Management, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. WM-18-24 |
| Abstract | The population of Pakistan is increasing and its freshwater resources are depleting. The irrigated areas are already under intensive cultivation demanding land and water potential of rainfed areas to be unlocked. Although, climate change is a global challenge, but its implications are more at local scale. Pakistan is more vulnerable to climate change, which is threatening country’s water and food security. Rainwater harvesting in rainfed areas can be deployed as not only a water source development, but also a climate change adaptation strategy. The demand, supply, storage and reliability are main considerations in rainwater harvesting system (RWHS). This research was conducted to analyze climate change and its impact on baseline and future irrigation water demands of selected high-value crops as well as simulation of supply, storage, reliability and potential of RWH in Pothohar. The trend analysis of historical and projected precipitation, maximum and minimum temperatures was done using combination of two non-parametric tests, Mann-Kendall and Sen’s slope to find the direction and magnitude of climate trend for Murree, Islamabad, Chakwal, Rawalpindi, Attock and Jhelum. The results showed that the historical precipitation had a non-significant decreasing trend at other five stations, with an increasing trend at Rawalpindi at a rate of 6.4 mm/year. The trend of maximum and minimum temperatures indicate significant warming in Pothohar at a rate of 0.006 oC/year and 0.012 oC/year during the last 3 to 4 decades. The future climate was projected using data from three Regional Climate Models (RCMs) and analysis of future climate indicated increasing trend of all three important climatic variables, i.e., precipitation, maximum and minimum temperatures. The projected climate indicated that although the future average annual precipitation was expected to increase at a rate 3.6 and 1.7 mm/year, however, there was a risk of seasonal droughts during spring and winter seasons as well as a warming trend due to an increase in maximum temperature at a rate of 0.01 and 0.046 oC/year and minimum temperature by 0.023 and 0.06 oC/year under RCP4.5 and RCP8.5, respectively. The district-wise baseline ETo values were also estimated and the same were 2.96, 3.24, 3.77, 3.30, 4.32 and 3.53 mm/day for Murree, Islamabad, Chakwal, Rawalpindi, Attock and Jhelum, respectively. The ETo and ETc in future were projected to increase, however, the irrigation water demands would first increase in near future (2020-2039), then decrease during mid and far future time periods because of more contribution of effective rainfall. The USDA SCS CN method for runoff estimation had been used for the simulation of supply to the RWHS and the Behavioral model was applied for simulation of storage size for RWHS. Then the reliability indicator was used to assess the performance of RWHS for high-value crop production. The storage capacity and the dimensions of RWHS were examined. The results showed that the RWH storage capacity of 9632, 14396 and 11261 m3/ha for a standard 10 hectares farm could reliably meet the irrigation water demand of high-value crops in Attock, Jhelum and Rawalpindi, respectively, however, the farm-level RWH was found less reliable in Chakwal. It was inferred from results that flexibility of 5-10% in design storage would be sufficient to meet the near future irrigation water demands of selected crops. The ArcSWAT model was used for identification of potential RWH sites and found that there were about 11,645 number of potential RWH sites with sub-basin area ranged from 0.75 ha to 1,500 ha, out of which around 3,000 sites had catchment area from 0.75 to 100 ha. The average annual runoff under baseline, RCP4.5 and RCP8.5 scenario was estimated to be 4407, 5067 and 4824 million cubic meters (MCM) per year. The potential of conversion of rainfed cultivated area to the irrigated area was also investigated and results were such that 76% of total rainfed cultivated farm in Attock, 26.6% in Chakwal, 100% in Jhelum and Rawalpindi could be brought under irrigated status through RWH intervention. |
| Year | 2018 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. WM-18-24 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Water Engineering and Management (WM) |
| Chairperson(s) | Shrestha, Sangam;Datta, Avishek ; |
| Examination Committee(s) | Babel, Mukand S.;Soni, Peeyush ; |
| Scholarship Donor(s) | World Bank;Punjab Agriculture Department, Pakistan; |