Water management policy analysis: Insight from a calibration-based inexact programming method

Predicting the impacts of water management policies under uncertainty can support policy-makers in making sound decisions. Most previous methods for policy-impact simulation lacked a calibration process that would allow model results to match observed values, and did not address the inherent uncertainties. To fill this methodological knowledge gap, an interval credibility-constrained positive mathematical programming (ICPMP) approach was first developed in this study for simulating the impacts of water management policies. This method improved over traditional positive mathematical programming in terms of uncertainty treatment. It also improved upon inexact programming methods through activating a calibration process. ICPMP was then coupled with a multi-attribute decision-making approach, leading to a simulation-evaluation method that could support the analysis and screening of policy alternatives. This method has been applied to an agricultural water management problem in northwestern China. Various policy alternatives corresponding to different water prices and varied fuzzy credibility levels of water availability were investigated. The impacts of these alternatives over farmers' income, irrigation water consumption, benefit per cubic meter of water, planting area, and fertilizer use were simulated through ICPMP. Forty policy alternatives with better indicator performances were selected to be comprehensively evaluated using the multi-attribute decision-making approach. The results indicated that when the decision-makers have a positive preference for water availability, the water price at the turning point of water use efficiency (i.e. benefit per cubic of water) was recommended. When decision-makers have conservative attitude towards water availability, it was recommended to keep the water price unchanged. Comparisons of ICPMP against traditional methods indicated that, ICPMP could generate more reliable results through incorporating uncertain information as inputs and reproducing actual situation. As well, solutions of ICPMP could provide in-depth analysis of the trade-offs between violation risk and system benefits. ICPMP and the associated simulation-evaluation method are also applicable to analyze other types of policies.

Automated summary

This study developed an interval credibility-constrained positive mathematical programming (ICPMP) method for simulating the impacts of water management policies. It improved upon traditional methods by incorporating uncertain information and reproducing actual situations. The ICPMP method was applied to an agricultural water management problem in northwestern China. Results showed that it generated more reliable results and provided in-depth analysis of trade-offs between violation risk and system benefits.