Quantifying biophysical constraint of Nature: Measuring Renewable Freshwater Resources at Multiple Scales

Water resources sustainability is the key component for transformation toward societal sustainability. This relationship between water resources sustainability and societal sustainability is based on the need of high congruency of functioning of natural and socio-economic systems and criticality at their interface. The first-order condition to make this transformation is the recognition by society of incorporation of two principles: the biophysical constraint of natural systems and the socio-economic restraint of human systems. In this context the socio-economic restraint should guide human activities that will cap overall throughput within the biophysical constraint of natural systems for the indefinite future. The biophysical constraint for sustainable water resource, as a measure of the limit of natural systems, is the rate of renewal of freshwater resources. To assure sustainable use of freshwater this rate of renewal must be used with caution to sustain both human needs as well as the needs of nature (ecological services). Methods for quantifying the rate of renewal of refreshwater resources for a given geographical location involves the use of systems analysis with appropriate sets of hydrologic (mostly streamflow), geologic, landuse, and meteorological data. These methods are well developed for applications in areas where there are sufficient holdings of the required data. We have found that such analyses are possible at large scales such as at the continental scale, and in many cases at the scale of individual countries, because for these scales there is generally sufficient data. However, at more refined scales the issue of data sufficiency becomes problematic, especially in more undeveloped parts of the world. Resolution of this issue requires the application of other data sources, including information gleaned from remote platforms and data collected on the ground within the regions of interest. This of course requires international collaboration among individuals involved in the endeavor to quantify freshwater resources. This presentation will show the use of the systems analysis approach for quantifying the renewable flux for the situation of relatively rich databases, such as in the United States and in Russia, and will outline some of the approaches that could be used for the very common situation where data are extremely limited, as in countries like Mongolia.