Assessment of agricultural economic impacts under climate change through drought Severity- Duration - Frequency curves

Abstract

A drought is a natural disaster of not receiving rain or snow over a period of time resulting in prolonged shortages in the water supply whether atmospheric surface water or groundwater A quantitative estimate of the probability of occurrence and the predicted severity duration of drought is important for the development of strategies in the water resources management This study aims to develop a streamflow drought severity – duration- frequency (SDF) curves to estimate the long-term financial impact due to lack of certainties in climate change and agriculture projections Severity was identified as the total water deficit volume to target threshold for a given drought duration Furthermore this study compared the SDF curves of two threshold level methods: fixed and monthly as well as evaluate the impacts of climate change on the SDF curves for the fixed threshold level The scenarios climate is focused on AR4 (A2 AB1 B2) from the general climate model Time series of the annual maxima values of duration and volume deficit indicated a similar trend of increasing and decreasing in different threshold level The fixed threshold level is the 70th percentile value (Q70) of the flow duration curves (FDC) which is compiled using all available daily streamflow The monthly threshold level in this study is the monthly varying Q70 values that was obtained from antecedent 12 months streamflow SDF curves were prepared and fitting statistical distribution to each one The approach continues with the impacts of climate change on the SDF curves for the fixed threshold level Likewise the methodology defines a water tariff price delimited by the drought duration and calculate the revenue loss scenarios in agriculture As a case study the approach is applied to the Kaoping River in Taiwan the main water supply source for agriculture industry but this study concentrates on the profit loss in agriculture The results show that the SDF curves from the fixed threshold level increase value of the volume deficit than the monthly threshold level in each period Drought deficit volume increasing rate was different in each class of duration–interval Similarly the SDF curves were varied under climate change the duration and severities from GFDL_CM2_1 GCMs of each scenario is higher than baseline and increasing of duration resulted to the increased value of the volume deficit with a non–linear trend Additionally the severity-duration-frequency- profit loss under the historical data is resulted to estimate the baseline scenario of damage cost in the water utility company In addition the anticipated profit loss the long term would serve as the initial estimate for financial contingency plan or community contingency funds In general the development of SDF curves can be proposed as a planning tool to mitigating and real-time management of drought effects in water resource management

Date of Award	2019
Original language	English
Supervisor	Pao-Shan Yu (Supervisor)