Assignment #9 - Compromise programming - instream flow - multiobjective

1) Article Reference
Shiau JT, Wu FC (2006) Compromise programming methodology for determining instream flow under multiobjective water allocation criteria, JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, 42(5), pp. 1179-1191

2) Summary
This paper presents a multiobjective approach for evaluating instream flow water allocation considering increasing water uses within the basin. This approach uses the concept of Range of Variability (RVA) Approach and the Indicators of Hydrologic Alterations (IHAs).
A case study is presented for the Kaoping creek in southwestern Taiwan. Extensive description of the hydrologic and water use characteristics of the basin is provided. Special concerns are related to endangered and endemic species. By date, instream flows are been provide to support the ecological health of the systems, but is believed that those releases are incapable of guarantying sufficient flow variation required for the sustainability of the aquatic biota. Tables presented monthly average inflow and water uses for agricultural and municipal uses within the basin.
For the optimization analyses of the water allocation schemes, a description of the methodology used is provide, including a short review of the Range of Variability Approach concepts and the overall degree of hydrologic alteration. A detailed table is provided to describe the IHAs used in the RVA. The IHAs are grouped in 5 different specifications which represent different hydrologic parameters.
A description of the weir (main diversion point) operation model is also provided. Within this description the operation of the weir and the different water uses are described.
The main goal of the weir is to supply the registered agricultural demand , the projected municipal water supply and the instream flow conditions. Considering the municipal water supply and the agricultural use, the objective is to minimize the shortages periods, represented by a shortage ratio.
To solve the minimization function, the authors used a Multiobjective compromise programming approach. The results evaluated the current schedule operation impacts on water shortages and hydrologic alterations, the effects of different instream flow releases ,the effects of weighting factors and the Ecological Effects of proposed instream flow release
The main conclusions of the paper were that the inclusion of the individual degrees of alteration associated with the 32 IHAs made possible to optimize the weir operation scheme through compromise programming and showed that the current instream releases do not meet minimum requirements for guarantee ecological health downstream.

3) Discussion
I enjoyed reading this paper as it gave me a better sense on the practical application of multi objective problem solving. I think this kind of optimization is very useful, as it really approaches real life problems. Usually there are more than one objective that almost always differ from each other. Although, I think the evaluation of the intream flow necessities could have been better evaluated.