Department of Civil Engineering, IIT-Hyderabad, Telangana 50285, India.
Department of Civil Engineering, IIT-Hyderabad, Telangana 50285, India.
Sci Total Environ. 2020 Jun 15;721:137736. doi: 10.1016/j.scitotenv.2020.137736. Epub 2020 Mar 5.
The climate and Land Use/Land Cover (LULC) changes evince the considerable impact on water balance components by altering the hydrological processes. So, the present work focuses on the evaluation of the combined impact of both the climate and LULC changes along with and without water storage structures on water balance components of the Krishna river basin, India under present and future scenarios with the help of Soil Water and Assessment Tool (SWAT). Sequential Uncertainty Fitting algorithm (SUFI-2) was used for the model calibration and validation, which were carried out at the Vijayawada gauge station. The coefficient of determination (R) and Nash-Sutcliffe efficiency (NSE) values obtained during the calibration period were 0.63 and 0.61, respectively, whereas, in validation, these values were found to be 0.61 and 0.56, indicates satisfactory results. The results showed that the model simulations and performance were significantly influenced by the presence of water storage structures, whereas the LULC changes were effective at the sub-watershed level. Future LULC maps of 2025, 2055, and 2085 were simulated from the Cellular Automata (CA) Markov Chain model, and they were used along with future climate projections to investigate its impact on water balance components. The climate model projects an increase of water balance components specifically, surface runoff, streamflow, and water yield, except for evapotranspiration in the future. Whereas, the future LULC changes may influence in offsetting the streamflow 20 to 30% reference to the observed flow. Thus, LULC changes were significantly influenced the model simulations; therefore, it is essential to consider the LULC changes along with climate scenarios in climate change studies. Overall, the surface runoff, water yield, and streamflow may increase by 50% under Representative Concentration Pathway (RCP) 4.5, and they may double under the RCP 8.5 scenario by the end of the century.
气候和土地利用/土地覆被（LULC）变化通过改变水文过程，对水平衡要素产生重大影响。因此，本研究借助土壤水和评估工具（SWAT），重点评估在考虑和不考虑储水结构的情况下，气候和 LULC 变化对印度克里希纳河流域水平衡要素的综合影响。利用序贯不确定性拟合算法（SUFI-2）进行模型校准和验证，校准和验证工作分别在 Vijayawada 测量站进行。校准期间，获得的决定系数（R）和纳什-苏特克里夫效率（NSE）值分别为 0.63 和 0.61，而在验证过程中，这些值分别为 0.61 和 0.56，表明结果令人满意。结果表明，模型模拟和性能受储水结构的存在显著影响，而 LULC 变化在子流域层面上有效。2025 年、2055 年和 2085 年的未来 LULC 图由元胞自动机（CA）马尔可夫链模型模拟，并与未来气候预测结合使用，以调查其对水平衡要素的影响。气候模型预测，未来所有情景下，除蒸散量外，水平衡各要素，特别是地表径流量、河川径流量和水量产率均会增加。而未来 LULC 变化可能会抵消 20%至 30%的观测流量。因此，LULC 变化显著影响模型模拟；因此，在气候变化研究中，考虑 LULC 变化与气候情景是至关重要的。总体而言，到本世纪末，在代表性浓度路径（RCP）4.5 情景下，地表径流量、水量产率和河川径流量可能增加 50%，在 RCP 8.5 情景下可能增加一倍。
