METHODS FOR ASSESSING ECOSYSTEM SERVICES FOR WATER FLOW REGULATION

Abstract

In the course of its functioning, the city’s blue-green infrastructure (BGI), among other ecosystem services (ES), provides water flow regulation services. These are not only economic benefits associated with minimizing flood mitigation losses, but also environmental benefits, which include the normalization of the water cycle. To justify decisions on preventing or reducing the effects of floods in cities, it is very important to quantify the ES of water flow regulation. However, to present time, there is no universal structure and clear mechanism for conducting such an assessment in difficult urban conditions. The purpose of this study is to develop a methodology for geoinformation assessment of water flow regulation ES provided by urban green spaces (UGS) based on remote sensing data using open-source GIS tools. In accordance with the goal, the study developed a methodology based on determining the effectiveness of the relevant function of both individual UGS and the entire city’s BGI. In accordance with the indicators that characterize the properties of green spaces that mainly affect water regulation within the basin, a set of estimated indicators for the assessment was substantiated. These are the characteristics that determine the volume of water runoff, which were generalised and combined into a single calculation parameter (Fall), the coefficient of water regulating capacity due to the quality characteristics of vegetation cover (ω_veg); the coefficient of water regulating capacity due to soil properties (K_soil); the coefficient of water regulating capacity due to the type of underlying surface (ω). These parameters make it possible to implement an assessment methodology that consists in the step-by-step determination of: water flow indicators within small river basins (sub-basins); the efficiency of performing the water flow control function of each individual green area (E_water control (g_a)), and the efficiency of water flow control within the river basin by all available BGI within its boundaries (E_water control). Effectiveness indicators, based on the Harrington’s desirability function, allow to determine the volume of ES water control provision (ES_water_control(BGI) / ES_water_control(g_a)). The assessment based on this methodology can be a useful tool in urban planning decision-making. It allows identifying green areas that require priority actions to improve their capacity to provide flood control and adaptation of urban areas to climate change.