| Author | Ghulami, Masoud |
| Call Number | AIT Diss. no.WM-17-01 |
| Subject(s) | Climatic changes--Water-supply--Afghanistan--Kabul Basin
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| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Engineering in Water Engineering and Management, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. WM-17-01 |
| Abstract | Afghanistan is a semi-arid and mountainous country which faced three decades of conflict. It is one of the most vulnerable countries in the world to climate change as it has very limited capacity to address the impacts of climate change. It has been also considered as a data-scarce region both temporally and spatially with limited capability to measure hydro-meteorological parameters with in situ gauges. The current study focuses on Kabul basin which lies in the northeast quarter of Afghanistan. It accountsfor thirty-fivepercent of the population’s water supply, and has the fastest population growth rate in the country. The main objective of this study is to understand the impacts of climate change on water resources and agriculture. To understand the impact on water resource, first of all,the performance evaluation of global datasets/remote sensed products is investigated in order to generate precipitation and temperature datasets for baseline period of climate change studies and developing hydrological model. Then a hydrological model is selected to understand hydrologic response of the Kabul basin and future projections of water availability using future climate projections. To understand the impact on agriculture, a study on farmers’ perception about climate change and its impacts on their agriculture is undertaken. Secondly, a crop model is used to evaluate the impacts of climate change on wheat yield.The gridded satellite/global precipitation time series data of CPC-RFE, GSMaP_MVK, TMPA, and APHRODITEare validated using the data from recently established precipitation gauge locations over the Kabul basin from 2004 to 2007, the common years of availability of all used datasets. These products are evaluated at different spatial and temporal resolutions (daily, monthly, and annual). The validation approach used here includes continuous (mean absolute error [MAE],root mean square error [RMSE], correlation [r], and multiplicative bias [Mbias]) and categorical (probability of detection [POD] and false alarmratio [FAR]) verification statistics. Furthermore, the spatial performance is evaluated by visual inspection as well as mapping the data and analyzing the distribution of precipitation as a function of elevation. The future predictions of precipitation and temperature under different RCP (Representative Concentration Pathways) scenarios are investigated from a set of recent CMIP5-GCMs (Coupled Model Inter-comparison Project Phase 5-Genral Circulation Models) after bias correction and downscaling. The GCMs’ output is downscaled and bias corrected to the stations using the lineardownscaling method. The values of all stations then are averaged over Kabul basin for each month and the changes are calculated for future periods of 2020s, 2050s, and 2080scompared to the baseline of 1971-2000. The values also are averaged over the season, winter and summer. The winter starts inNovember and ends by April. The summer is also a period of six months from May to October. For the assessment of future climate predictions on water resources, the bias-correctedprecipitation and temperature are used as input to the J2000 hydrological model, which is a physically distributed model with separate modules for snow and glacier contributions.Two field surveys using questionnaire are done to understand the farmers’ perception about climate change and their adaptation measures. The descriptive statistics is then used to summarize the results of the surveys. AquaCrop model is used to determine the impacts of climate change on wheat yield, which is the most dominant crop in the study area and accounts for 80% of planted areas of cereals in Afghanistan. The impact of shifting the planting date and using full or deficit irrigation as agro-adaptation measures is then investigated. ivFor hydrological applications, it is essential to quantify precipitation. The availability of satellite-basedprecipitation products and gridded interpolated datasets provides a great opportunity for those regions suffering from poor spatial and temporal sampling of precipitation. The estimates from four tested products showed a relatively good detection of precipitation distribution and precipitation amounts for most cases.The results of continuous and categorical verification statistics suggest that the APHRODITE dataset performs better than other gridded datasets for the study basin. APHRODITE temperature data is also found very suitable for the study area after comparison with the surface observations. The results of trend analysis suggest that the temperature has been increased over last five decades while such a clear trend for precipitation is not detected. The median of the results from all 8 GCMs suggests an increasing trend in maximum and minimum temperature in the future, as compared to the baseline. The increases for maximum temperature range from +1.7°C to +4.1°C under RCP 4.5 and +1.7°C to +6.3°C under RCP 8.5. The increases for minimum temperature range from +1.5°C to +3.8°C under RCP 4.5 and +1.4°C to +6.0°C under RCP 8.5.The projections for precipitation mainly show a decreasing trend under both RCPs, with variations ranging from -19% to -6% under RCP 4.5 and -18% to 3% under RCP 8.5.The results of J2000 hydrological model show that the model performed well and can be used to reproduce the hydrological response of the basin. As per the predictions, future runoff ranges between -14% and +49% under RCP 4.5 and between -16% and +100% under RCP 8.5 during the 21stcentury. The median values varying between -9% and +22%.Based on the results of field surveys, climate change is already perceived by many farmers in the selected districts of the study area. As it was expected from climate trend analysis, most of the farmers agreed on increasing temperature, but there was no clear trend for precipitation. While the amount of precipitation might not change significantly, water resources have decreased. This might be due to the changes in precipitation and runoff distribution. Broadly, the changes in the water resources in the study areas might bedue to climate change or/and increase of water usage as a result of increased population. The main adaptation measures taken by farmers include planting trees and changing the crop type and crop calendar.AquaCrop modeling results for winter wheat show that under future climate change scenarios, the yield will increase. The main reason for this increase is the decrease in the stress related to cold temperature. Shifting the planting date and applying different levels of irrigation were examined by the AquaCrop model and the results show that these measures can be effective in maximizing the yield.This study recommends that the future projections of temperature and precipitation are highly uncertain and policy makers should include a range of projections while making the decisions for development plans and adaptation strategies. Temperature is projected to increase in future for the study area but the results suggest that it might create further opportunities due to increase in the water availability and decrease in the cold temperature stress for the crops. However,lackof infrastructure might lead to further problems due to the possibility of more frequent and extreme floods and droughts. This study can be used as an outlinefor other river basins in Afghanistan |
| Year | 2017 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. WM-17-01 |
| Type | Dissertation |
| School | School of Engineering and Technology |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Water Engineering and Management (WM) |
| Chairperson(s) | Babel, Mukand S.; |
| Examination Committee(s) | Shrestha, Sangam ;Kawasaki, Akiyuki ;Jourdain, Damien ;Shrestha, Mandira; |
| Scholarship Donor(s) | Ministry of Foreign Affairs, Norway; |
| Degree | Thesis (Ph. D.) - Asian Institute of Technology, 2017 |