Using the InVEST Model to Assess the Impacts of Climate and Land Use Changes on Water Yield in the Upstream Regions of the Shule River Basin

An improvement on the assessment of ecosystem services value of urban wetlands under consideration of water yield at regional scale

Urban wetlands are gaining more attention and showing more important play in the sustainability. Surge findings are attached on the assessment of Wetland Ecosystem Service Value (WESV) in urban areas. While determining WESV in urban areas, it is still difficult to capture the nature of wetlands due to neglecting the impact of related impervious surfaces. It is necessary to improve the existing evaluating methods of WESV when seeking the truth. In order to narrow this issue, based on InVEST model, this study employed Equivalent Factors (EF) to determine WESV in urban areas with a case of Hengyang City, China. The main materials of this study included high-resolution images, DEM, precipitation, evapotranspiration, soil, vegetation, and statistical yearbook of the case. By comparing the uncorrected results with precipitation corrected and water yield corrected results of WESV, this study confirmed that: (1) the corrected results can reflect more real status than uncorrected; (2) in terms of EF, the water yield factor is more conducive to finding the truth than precipitation. Through this study, the water yield factor can effectively reduce the adverse effects of climate and improve the accuracy when determining WESV in urban areas.

Spatiotemporal variations and tradeoff-synergy relations of ecosystem services under ecological water replenishment in Baiyangdian Lake, North China

Understanding dynamic variations of ecosystem services (ESs) and their tradeoff-synergy relations under ecological water replenishment (EWR) is conducive to the formulation of effective eco-environmental management strategies. In this study, spatiotemporal variations of three leading ESs, namely habitat quality, carbon storage and water yield services influenced by EWR in Baiyangdian Lake, North China from 1991 to 2019, were investigated using the "Integrated Valuation of Ecosystem Services and Tradeoffs" (InVEST) model, and their tradeoff-synergy relations were quantitatively assessed with correlation analysis methods. Our results showed that habitat quality had continuously declined, whereas it got a steady improvement after the year of 2015. Total carbon storage was relatively stable, and the volume of total water yield and precipitation showed the same variation trend. Overall, EWR promoted the maintenance and improvement of ESs. Tradeoff-synergy relations among ESs varied with time and space. Temporally, there was an obvious synergistic relation between habitat quality and carbon storage services. Spatially, these two ESs were synergistic in the southern, central and eastern parts of the lake, while they had a tradeoff relation in the north; and there were no tradeoff-synergy relations between the water yield service and these two services. This study confirmed the importance of zoning management and comprehensive multi-factor management based on spatial and temporal differences of ESs, and can offer a scientific basis for adaptive eco-environmental management strategies for wetland restoration.

Landscape Pattern Change and Ecological Effect in a Typical Mountain-Oasis-Desert Region in the Northwest Region of China

China has experienced dramatic changes in its land use and landscape pattern in the past few decades. At present, a large number of studies have carried out in-depth and systematic analyses on the landscape variation and its ecological effects in Central and Eastern China, but research on the northwest arid region is relatively deficient. In the present study, the city of Hami, which is located in the northwest arid region of China, was selected as the study area to investigate the responses in the habitat quality, water yield and carbon storage to land use and cover change during 2000-2020. We found that (1) during the entire study period (2000-2020), the variation intensity of the first decade (2000-2010) was significantly greater than that of the second decade (2010-2020), and the conversion between desert and grassland played a dominant role in the conversion among these land types. (2) The maximum value of the habitat degradation degree in Hami city increased during the study period, indicating that the habitat presented a trend of degradation. (3) The total carbon storage in Hami city was approximately 11.03 × 10⁶ t, 11.16 × 10⁶ t and 11.17 × 10⁶ t in 2000, 2010 and 2020, respectively, which indicated an increasing trend. (4) According to the calculation, the average water yield and the total water conservation showed a decreasing trend in the study area. The corresponding results will help to formulate protective measures that are conducive to the restoration of ecosystem functions in extremely arid regions.

Exploring the Relationship between Ecosystem Services under Different Socio-Economic Driving Degrees

The large-scale transformation of natural ecosystems to socio-economic development land types under human activities was a primary reason for the decline of regional ecosystem services. It is a key issue for regional ecosystem planning and management to reveal the relationship between ecosystem services of different land use types under different socio-economic driving degrees. However, the current related research was not in-depth. Based on the land use data of Wuhan City in 1980, 1990, 2000, 2010, and 2020, this study classified land use into three categories according to the different degrees of human activities on natural ecosystem development: the land use of a natural ecosystem (LUNE), the land use of a productive ecosystem (LUPE), and the land use of a socio-economic system (LUSE). The InVEST model was used to simulate five ecosystem services (grain yield, water yield, carbon storage, habitat quality, and water purification), and the spatio-temporal distribution and functional transformation of the three land use types were analyzed. Results showed that with the intensified urban expansion in Wuhan, the LUSE types increased to 2.7 times that of the original. However, the natural land types basically maintained a stable area, coupling with the large-scale transformation between the LUPE and LUSE types. Land use change resulted in significant spatial changes of five ecosystem services, especially carbon storage and habitat quality. The correlation analysis indicated that the five kinds of ecosystem services mainly showed a synergistic relationship, meanwhile the LUSE type denoted the most significant correlation with ecosystem services among these three category types. This study indicated that besides the protection of natural ecosystems, the LUSE type would become the key land use type in the planning and management of improving regional ecological function.

Land Cover Change and Water Quality: How Remote Sensing Can Help Understand Driver–Impact Relations in the Lake Titicaca Basin

The increase of human interventions and developments are modifying the land use/land cover (LULC) of the global landscape, thus severely affecting the water quality of rivers and lakes. Appropriate management and effective policy developments are required to deal with the problems of surface water contamination around the globe. However, spatiotemporal variations of water quality and its complex relation with land cover (LC) changes, challenge adequate water resources management. In this study, we explored the use of remote sensing to relate LC change in the Katari River Basin (KRB) located in the Bolivian Andes and water quality on the shores of Lake Titicaca, in order to support water management. An unsupervised classification of Landsat 7 satellite images and trajectory analysis was applied to understand the modifications of LC through time. In addition, water-quality indicators at the outlet of the basin were retrieved from remote-sensing images and its temporal behavior was analyzed. The results show that the expansion of urban areas is the predominant environmental driver in the KRB, which has great impact on the water quality of Lake Titicaca. We conclude that there is a strong link between the rapid growth of urban and industrial areas with the detriment of river and lake water quality. This case study shows how remote sensing can help understand driver–impact relations.

Using InVEST to evaluate water yield services in Shangri-La, Northwestern Yunnan, China

Water yield is an ecosystem service that is vital to not only human life, but also sustainable development of the social economy and ecosystem. This study used annual average precipitation, potential evapotranspiration, plant available water content, soil depth, biophysical parameters, Zhang parameter, and land use/land cover (LULC) as input data for the Integrated Valuation of Ecosystem Service Tradeoffs (InVEST) model to estimate the water yield of Shangri-La City from 1974 to 2015. The spatiotemporal variations and associated factors (precipitation, evapotranspiration, LULC, and topographic factors) in water yield ecosystem services were then analyzed. The result showed that: (1) The water yield of Shangri-La City decreases from north and south to the center and showed a temporal trend from 1974 to 2015 of an initial decrease followed by an increase. Areas of higher average water yield were mainly in Hutiaoxia Town, Jinjiang Town, and Shangjiang Township. (2) Areas of importance for water yield in the study area which need to be assigned priority protection were mainly concentrated in the west of Jiantang Town, in central Xiaozhongdian Town, in central Gezan Township, in northwestern Dongwang Township, and in Hutiaoxia Town. (3) Water yield was affected by precipitation, evapotranspiration, vegetation type, and topographic factors. Water yield was positively and negatively correlated with precipitation and potential evapotranspiration, respectively. The average water yield of shrubs exceeded that of meadows and forests. Terrain factors indirectly affected the ecosystem service functions of water yield by affecting precipitation and vegetation types. The model used in this study can provide references for relevant research in similar climatic conditions.

Water Yield Modelling, Sensitivity Analysis and Validation: A Study for Portugal

The spatially explicit assessment of freshwater is key to introduce the ecosystem services (ES) concept into decision-making processes. Many tools are being developed to model water balance and to analyze the effects of meteorological conditions on water ES behaviors at multiple spatial scales. The current study uses the InVEST Annual Water Yield Model (WYM) to assess water availability in watersheds of the mainland of Portugal. The methodology included sensitivity analysis to test different parameters of the model and validation using the European Environment Agency (EEA) database on the quantity of Europe’s water resources. To evaluate the models’ sensitivity, Pearson’s correlation coefficients and statistical methods were calculated for each simulation. Results at the national level show a correlation coefficient of 0.803 with statistical significance for 0.01 one-tail. Water yield was underestimated by 56.5 mm/ha/year in the North of the country and overestimated by 58.1 mm/ha/year in the South. This difference was explained through the spatial-temporal assessment of the main climatic variables used as input. This study contributes to a methodology to assess the level of confidence in the WYM outputs and can be used to support the trustworthiness of water availability studies, using open-access data and software.