Comparing industrial and domestic water demand of two GHMs, PCR- GLOBWB and WaterGAP

Abstract

Global Hydrological Models (GHMs) have often been used to predict water demand. In this study the domestic and industrial water demand of two of these GHMs, WaterGAP and PCR-GLOBWB, is compared and assessed. The aim of this research was to improve these GHMs by evaluating the difference between these models and the causes of these differences. This study increased the knowledge of the working of the models by comparing them. It contributed to the insights in industrial and domestic water demand. The models were compared based on their base year (2005) water consumption and withdrawals and on the withdrawals of the climate scenario, “the sustainability quest”, which gave projections until 2050. Differences in outcomes between these models can be caused by differences in input data, model structure or parameters.

In the base year comparison several countries, which were found to have a large difference in base year outcome, were selected for further analysis of the withdrawal projections. The first step in finding the cause of the difference in outcome was comparing the base year data input of the two GHMs for these counties. The second step was analysing the projected water withdrawals. Withdrawals of the two GHMs and two extra withdrawal scenarios, which are based on a fusion of the model structure, parameters and data input of the two models were analysed. The countries are categorised in several ways, of which by Hydro-Economic region (HE-region) was the most elaborated. At last the parameters that cover the effect of technology were separately analysed, for the domestic sector.

The base year comparison showed that in general the domestic water withdrawal and consumption of PCR-GLOBWB was higher than that of WaterGAP, but that for the industrial sector both models were highest in turn. The analysis of the future projections showed that in HE-region 1, the poor and water secure countries, the data input were most important in causing differences in the domestic sector. For countries of the industrial sector in that region next to the data input, the models structures were a cause of the differences. In the other HE-regions the causes were more country specific and general trends were missing. There are three countries in the domestic sector; Lithuania, Turkey and Ukraine, as well as three in the industrial sector; Romania, the Russian Federation and Ukraine, of which the differences in outcomes are caused by the data input, according to the base year comparison and the analysis of the water withdrawals. The parameter of PCR-GLOBWB that covered the effect of technology had a more diffuse and strong effect than that of WaterGAP.