# Multidimensional Assessment of Lake Water Ecosystem Services Using Remote Sensing
## 1 Introduction
This scalability should correspond to the aggregated level of political units that transforms scientific findings into practical applications. In this paper, we aggregated the assessment results derived from remote sensing data at the county level. We proposed a quantitative approach that reflects the natural situation and provides a promising mechanism for linking scientific information to decision-making via demographic, landscape, and economic statistics based on administrative divisions. Some of the limitations of existing research can be summarized as follows: (1) While the ecosystem services assessment has made significant progress in recent decades, existing methods largely focus on estimating the total output from ecosystems [45; 46; 47; 48], which cannot reflect the ecosystems in full-spectrum; they cannot distinguish the ecosystems with the same assessment results but in various sizes. For example, it is unreasonable to equate a lake covering an area of a hundred hectares to another lake covering twenty hectares just because they have the same water provisioning output. They also put the same assessment results on the ecosystems with an opposite trend. For instance, a progressive ecosystem whose assessment result has risen to a certain threshold should be distinguished from a deteriorating ecosystem whose result has fallen to this threshold. (2) In terms of temporal scale, few studies followed a long continuous timeline (over 20 years). Most existing research is limited to a short time period [2; 49; 50; 51; 52; 53]. (3) From a spatial perspective, most existing studies mapped the spatial distribution of ecosystem services; few studies explored the spatial characteristics and changes over time [54; 55; 56; 57; 58]. (4) Even though numerous research targets ecosystem services, quantitative relationships between influencing factors and ecosystem services have not been revealed precisely [59]. (5) Although the potential of remote sensing application in ecosystem services assessment has been explored gradually, the remote sensing-based results are not available at the decision-making level because these results are based on natural boundaries rather than county boundaries [49; 60; 61; 62],which is challenging to apply in policymaking, measures taken, and practical management. All of the requirements mentioned above call for systematic quantification studies. Compared with previous studies, the highlights of this paper are as follows: (1) We expanded the water provisioning ecosystem services assessment from an 'output' perspective to an 'output-efficiency-trend' multidimensional framework ([PERSON] et al., 2017), assessing ecosystem services from outputs, efficiency, and trend simultaneously (see Figure 1). Thus, some neglected information in traditional single perspective assessment can be revealed. (2) We analyzed 21 years of water provisioning ecosystem services in the study area, characterizing the changes over a long time period. (3) We revealed the spatial distribution characteristics via exploratory spatial analysis methods, identified and classified the degradation zones, and put forward the priorities in lake ecosystem management. (4) We constructed a model to explore the quantitative relationships between the main influencing factors and the multidimensional assessment results. (5) We analyzed the water provisioning services derived from remote sensing data at the county level, making it available to policymakers and natural resource managers as a reference in practical works.