Evaluating the coordinated development of social economy, water, and ecology in a heavily disturbed basin based on the distributed hydrology model and the harmony theory

Abstract

The coordination of social economy, water, and ecology is an important foundation for sustainable development. However, the interaction among social economy, water, and ecology are complex. The data scales between socioeconomic factors (normally at the spatial scale of the administrative region and the temporal scale of a year or month) and river water quality and ecological factors (normally at the spatial scale of a sub-basin and the temporal scale of an instantaneous value) do not match. Therefore, many current regulation methods do not sufficiently consider the interaction mechanisms between socioeconomic, water, and ecological factors or cannot adequately deal with the scale of the data. In this study, we proposed a new framework to assess the coordinated development of social economy, water, and ecology (SWE) by integrating the distributed social economy-water-ecological model (SEWE) and the harmonious regulation model. We built the SEWE model by coupling a rainfall-runoff model, river water quality, and ecological models; we built the harmonious regulation model based on the harmony theory method. We applied the proposed method and framework to the Shaying River Basin, which exhibited typical characteristics of multiple sluices and dams, high pollution, and significant human activities. Results indicated that the coordinated development level of the SWE in the Shaying River Basin was poor, with the average coordination degree varying from 0.39 to 0.60. The average growth rate of the coordination degree of socioeconomic indicators was greater than that of the river water quality and ecological indicators. The coordination degree of water ecological indicators was small with a decreasing trend. These results indicated the increasing impact of socioeconomic development on river water quality and ecology. Therefore, the Shaying River Basin should focus on ecological and environmental restoration, such as the effective control of pollution draining into rivers. The proposed methods and framework could contribute to the integrated water resource management of the basin.

Introduction

Water is a basic but indispensable and strategic natural resource for human survival (Yang et al., 2015). Ecology and the environment have important links between human and nature (Levin and Unsworth, 2013, Ives et al., 2017). Today, due to the rapid development of human society, problems associated with water resources, ecology, and the environment have become key factors hindering development. It is necessary to study coordinated development by examining the relationships among the social economy, water, and ecology (Estoque and Murayama, 2017, Vollmer et al., 2018). In our study, we considered the social economy, water, and ecology as a single system that consisted of a socioeconomic subsystem, a water subsystem, and an ecological subsystem. We described each subsystem using certain indicators. Specifically, we described the social economy according to indicators that reflected the level of social development, we described the water according to indicators that reflected the state of river water quantity and quality, and we described the ecology according to indicators that reflected only the state of river water ecology. We based the selection of these indicators on in-depth research of their interaction mechanism and actual conditions in the study areas.

However, it is difficult to deal with the mismatched space-time scales inherent in socioeconomic data and in river water quality and ecological data (De Lange et al., 2010, Hufnagl-Eichiner et al., 2011, Chaffin and Gunderson, 2016, Vigiak et al., 2018). Current evaluation and regulation methods based on mathematics and statistics fail to consider the interaction mechanisms between socioeconomic, river water quality, and ecological factors (Cui et al., 2019). Therefore, new research ideas are necessary. In this study, we propose a framework by integrating the distributed social economy-water-ecology model (SEWE) and the harmonious regulation model (Luo et al., 2018a).

Compared with lumped models, distributed hydrological models account for more of the spatial heterogeneity of hydrological factors, and their parameters have explicit physical meanings (Stisen et al., 2008, Schröter et al., 2011, Bhatt et al., 2014, Liu et al., 2015, Koch et al., 2016, Zhang et al., 2016). Therefore, they have developed rapidly since first being proposed, particularly with the successful application of geographic information technology and remote-sensing technology in hydrological modeling (Kang and Merwade, 2011, Soulis, 2013, Sanzana et al., 2017). Currently, distributed hydrological models that consider the interaction mechanism of the social economy, water, and ecology have attracted attention with the increasing complexity of the human-water relationship (Liu et al., 2014, Sivapalan, 2015, He et al., 2018). For example, Rosegrant et al. (2000) introduced an integrated economic-hydrologic modeling framework that accounted for the interactions among water allocation, farmer input choice, agricultural productivity, nonagricultural water demand, and resource degradation; Cai et al. (2003) developed a new, integrated hydrologic-agronomic-economic model; Ahrends et al. (2008) developed a coupled model system that included a distributed hydrological model and an economic optimization model. Due to a lack of in-depth research on the interaction mechanisms between natural and social water cycle factors and their interaction with river water quantity, quality, and ecological indicators, few distributed models have been built that consider the complex interactions of the social economy, water, and ecology factors as a whole. This limits the application of distributed models in heavily disturbed basins. In this study, we attempted to build an integrated model, the distributed social economy-water-ecology model (SEWE) by coupling the rainfall-runoff model, river water quality, and water ecological models to conduct a comprehensive simulation of socioeconomic factors, including river water quality and water ecological factors.

In the literature, considerable research has been conducted on the relationship between humans and nature (Flint et al., 2013, Motesharrei et al., 2014, Fischer and Eastwood, 2016, Augustine and Dolinting, 2016, Yan et al., 2018), the relationship between humans and water (Mehta, 2014, Choi et al., 2017, Bao and Zou, 2018), and the impact of socioeconomic development on basin ecology or the environment (Zessner et al., 2017, Cheng et al., 2018, Islam et al., 2018). For example, Mohamad and Momcilo (2009) studied the impact of human activities on the water system through the response of flood peak flow to urbanization and climate change; Zuo et al. (2016) analyzed the harmonious development level between the socioeconomic system and the river-lake system in Xiangyang City using the harmony theory method; and Albuquerque et al. (2018) introduced the niche construction theory (NCT) to investigate the effects of chronic anthropogenic disturbances on the environment. Few studies, however, have been conducted on the coordinated development of the social economy, water, and ecology from a systematic perspective.

In this study, we proposed a new idea to study the coordinated development of the social economy, water, and ecology by integrating a distributed hydrological model and a harmony regulation model (see Section 3.1). The core of this approach is to build the SEWE model, which considers the interaction mechanism of social water-cycle processes (water withdrawal, water use, water consumption, drainage, and sewage) and natural water-cycle processes (rainfall-runoff), and to integrate this model with the harmonious regulation model. First, we built an index system from the aspects of social economy, water, and ecology (see Section 3.2 for details); second, we built the SEWE model by coupling the rainfall-runoff model, river water quality model, and water ecological model, followed by a social economic-water-ecological harmonious regulation model based on the harmony theory method. We used the simulation outputs of the SEWE model as the inputs for the harmonious regulation model. The combination of the SEWE model and the harmonious regulation model has the advantage of dealing with the different spatiotemporal scales of data (see Section 3.1) and solving the limitations of the harmonious regulation model and some similar regulation methods without considering the interaction mechanisms among social economy, water, and ecological factors in their coordinated development studies. Finally, we developed a framework for the coordinated development of the SWE (see Section 3.1).

As a case study, we applied the proposed method and framework to the Shaying River Basin. In recent years, rapid industrial development and urban domestic pollution have had a serious impact on the river water ecology and environment of the basin, leading to the serious deterioration of river water quality and ecology. Pollutants are mainly concentrated in the middle and lower reaches of the basin (Luo et al., 2019). According to our field survey and experiments (2012–2015), the riverbank is severely hardened in many locations throughout the basin. Due to long-term human interference, the habitat of aquatic organisms is constantly changing. The newly formed river habitat environment has a selective effect on river organisms, leading to changes in the community structure of organisms. We detected few aquatic species in our experiment and most of them are pollution-tolerant.

The paper is organized as follows: the study area and data are given in Section 2, followed by the construction of the distributed social economy–water–ecological model (SEWE) with consideration of the interaction mechanism of socioeconomic, water, and ecological factors by coupling the rainfall-runoff model, river water quality model, water ecological model, and a harmonious regulation model based on the harmony theory method (see Section 3).

In our study, we combined the SEWE model and the harmonious regulation model to deal with the different spatiotemporal scale of data and to make up for the insufficient consideration of the interaction mechanism between the socioeconomic factors and the river water quality and ecological factors by the harmonious regulation model. We formed a new framework for studying the coordinated development of the social economy, water, and ecology (see Section 3.1). We then applied the proposed method and framework to the Shaying River Basin, which exhibited typical characteristics of multiple sluices and dams, high pollution, and significant human activities (see Section 4).