Hydrological Ecosystem Services Research Articles

Hydrological modeling and scenario analysis for water supply and water demand assessment of Addis Ababa city, Ethiopia

Study regionAddis Ababa, capital city of Ethiopia. Addis Ababa’s surface water reservoirs and groundwater infrastructures are in the Akaki watershed of the Awash Basin. Study focusThis study integrates a hydrological model, socioeconomic data, and different water management scenarios to investigate the current and future water supply and demand. Baseline water supply and water demand data are obtained from Addis Ababa Water and Sewerage Authority. The Soil and Water Assessment Tool (SWAT) model was used to simulate reservoir sedimentation and water quantity in the Akaki watershed. The city’s water demand projection is based on the standard public water demand requirement and projected population. The study considered five scenarios to assess the gaps between water supply and demand. New hydrological insights for the regionSimulation results showed that the area upstream of the existing reservoirs has the potential to supply 651,452 m3/day of surface water; however, currently, the reservoirs are supplying only 224,658 m3/day of water. With an optimistic scenario of planned reservoirs and groundwater boreholes becoming operational by 2029, water supply will only meet demands through 2035. Afterwards, the gap between water supply and demand will increase, due to an increase in population. Therefore, additional water supply projects, effective water use, and maintaining critical hydrological ecosystem services are required to bridge the gap between water supply and demand.

Application of multi-agent decision-making methods in hydrological ecosystem services management

In this paper, a methodology is presented for managing hydrological ecosystem services by taking into account the hierarchy of stakeholders involved in the decision-making process. With this in mind, a water allocation model is first used for allocating water resources to demands. Then, several ecosystem services (ESs)-based criteria are defined to evaluate hydrological ESs of water resources management policies. A set of water and environmental resources management strategies (alternatives) are defined for decision-makers, and several drought management strategies are determined to decrease the area of key crops and water demands of agricultural nodes. To model a multi-agent multi-criteria decision-making problem for managing hydrological ESs, three main steps are considered as follows:•Different ES-based criteria (i.e., economic profit, NPP,11Net Primary Productivity and ecological index) are defined, and their grade-based values are estimated.•Several strategies are defined for stakeholders at different levels.•A recursive evidential reasoning (ER) approach, which considers a hierarchical structure for decision-makers and a leader-follower game, is used to select the best strategy for each decision-maker.The applicability and efficiency of the methodology are illustrated by applying it to a real-world case study. The methodology is general and can be easily applied to other study areas.

Supply and demand dynamics of hydrologic ecosystem services in the rapidly urbanizing Taihu Lake Basin of China

Although it is challenging to integrate supply and demand to comprehensively understand urbanization effects on ecosystem services, this knowledge is essential, especially in rapidly urbanizing areas. A spatially explicit approach was developed here to synthesize supply and demand dynamics of the two most important hydrologic services in the rapidly urbanizing Taihu Lake Basin (TLB) of eastern China. The supply of water purification (WPS) and flood mitigation (FMS) were measured as nitrogen removal and runoff retention, respectively. Whereas the demand for water purification (WPD) was quantified as the difference between total and permitted nitrogen loading based on relevant water quality standards, the demand for flood mitigation (FMD) was estimated as the vulnerability to potential flood damage, including economic losses and causalities. We found a spatial mismatch where high WPS and FMS occurred in mountainous areas while high WPD and FMD concentrated in urban and agricultural areas across the basin. WPS and WPD decreased by 10% and 20%, respectively during 2000–2015, due mainly to loss of croplands to urban expansion. This was also the main cause of decreased FMS by 7% but increased FMD by 67%, which underscored the importance of conserving croplands in rapidly urbanizing regions of the TLB. Overall, land use composition had strong associations with WPD (r2 ≥ 0.57) and FMS (r2 ≥ 0.38) at the sub-basin scale, while the configuration of multiple land uses, such as urban sprawl, cropland fragmentation, and riparian buffers were crucial in influencing WPS. In comparison, FMD was most sensitive to urban expansion (r2 = 0.74), economic development (r2 = 0.81), and population growth (r2 = 0.93). These findings provide new insights into sustainable land management for coordinating supply of and demand for hydrologic services in the TLB and other urbanizing watersheds of the world.

Invasion in the riparian zone: What is the effect of Pteridium arachnoideum on topsoil permeability?

Pteridium arachnoideum is a cosmopolitan, allelopathic, pervasive species which is expanding its occurrence in many regions of the tropics. Yet, the ecohydrological effects of such colonization is virtually unknown especially when it occurs in riparian zones which are expected to perform many important ecosystem services. The objective of the present study was to evaluate the influence of Pteridium colonization on topsoil permeability in riparian zones. To do that, we selected two similar riparian zones: (i) dominated by Pteridium arachnoideum and (ii) under tropical forest. We performed infiltration, water repellency (dry and wet season) and penetration resistance measurements to evaluate soil permeability. The infiltration capacity was significantly lower in Pteridium compared to riparian forest. We attribute this reduction to the significant increase in both water repellency in the dry season and soil penetration resistance in the soil under Pteridium. Water repellency, though still present in the wet season in both riparian zones, had no significant difference. Our results show that, despite the loss of biodiversity with Pteridium invasion, water repellency has a clear reduction in the wet season which likely benefits infiltration. Thus, basic hydrological ecosystem services can probably still be provided by such invaded riparian zones.

Fluvisols Contribution to Water Retention Hydrological Ecosystem Services in Different Floodplain Ecosystems

Water retention is an important hydrological ecosystem service of active floodplain soils. The aim of the study was to evaluate the soil chemical, physical, and hydrological properties in Fluvisols in three different ecosystems that have an impact on water retention hydrological ecosystem services (WRHESs). We selected 16 localities along the Štiavnica River in Central Slovakia, 8 located in riparian zones (RZ), 5 in arable lands (AL), and 3 in grasslands (GL). Soil samples were collected from two layers (0–10 and 20–30 cm). In the laboratory, the soil physical (soil texture) and soil chemical properties (pH, soil organic carbon content, humic and fulvic acid ratio) were determined. Using undisturbed soil samples, the soil physical characteristics (particle density, bulk density, porosity, and actual soil moisture–SMa) were measured. With the help of pedotransfer functions, hydrological soil properties (field water capacity–FWC, wilting point–WP, available water capacity–AWC) were estimated. The recorded properties differed between the localities, ecosystems, and two layers. The SMa values showed a higher soil water retention potential of extensively used ecosystems, such as GL and RZ. However, the hydrological properties estimated by pedotransfer functions (FWC, WP, AWC) showed a higher soil water retention potential in AL localities. This indicated that for calculations, selected pedotransfer functions (particle size fractions, organic matter, and bulk density) and other soil or ecosystem properties (e.g., vegetation cover, meteorological conditions) have an impact on WRHESs. One such soil factor can be the quality of organic matter. On the basis of the results of the ANOVA, significant differences emerged between the different ecosystems for selected basic chemical, physical, and hydrological properties. The effect of the soil layer on the soil properties was revealed only in the case of SOC. The results indicated the effect of different ecosystems on soil WRHES and the importance of extensively managed ecosystems, such as RZ and GL. From this point of view, the reduction in the RZ and GL areas during a period of the last 70 years is negative. The findings should be taken into account in future sustainable floodplain management and landscape architecture.

From simple to complex – Comparing four modelling tools for quantifying hydrologic ecosystem services

The pursuit of good management of our waters poses permanent challenges to the whole society. Decision-makers often need to define appropriate and sustainable strategies on interdisciplinary topics, like water management issues. The rapidly evolving quantification and mapping of hydrologic ecosystem services (HES) is putting hydrologic and water management issues into an ecosystem services (ES) framework, which can be a step towards reconciling different aspects of land use and water management. Different tools can be used for modelling HES, with a wide range according to their basic properties, e.g., structure, methodology, computational needs, data requirements, reliability, controllability. As a result of that, the numeric values, spatial patterns, and reliability of HES assessments and the uncertainties in their results may differ significantly.In this paper, we covered almost the whole palette of HES mapping tools with regards to modelling approach: we used InVEST, SWAT and two novel rule-based matrix models for the same pilot area, the 1530 km2 hilly catchment of the Zala River (Hungary). We mapped three HES: flood control, erosion control and nutrient (total phosphorus) retention. Our aim was to examine the relevance of the differences between the HES mapping tools through analysing the spatial differences between the results obtained with the applied. We carried out spatial similarity tests and hotspot analysis at the computational unit level for the individual HES and in an aggregated way as well.As a result of the spatial pattern similarity tests, InVEST and the matrix models showed moderate to strong correlation (p < 0.001) for each HES. Due to that, the novel matrix models could be considered as robust HES mapping tools on a larger spatial scale (regional or larger). InVEST appeared to be the most efficient HES mapping tool considering computational demand, result reliability, and data- and expertise requirements. The results of our study draw attention to the importance and actual shortcomings of the land use and land cover (LULC) structure in the riparian zone. We pointed out that the studied HES in agricultural areas close to the watercourse are often disservices (negative HES were provided with the actual LULC scenario compared to a non-vegetated LULC scenario) due to the nutrient loads from fertilization. We found that parts of the best and worst HES provisioning areas (hotspots and coldspots) could be delineated without hydrologic modelling, because their unfavourable combination of environmental factors and LULC conditions themselves determine these areas to be hotspot or coldspot.

Mechanism of payments for hydrological ecosystem services in the Watershed of the Piray Miní stream

To promote the conservation and forest hydrological restoration of the ecosystems located in the watershed of the Piray Miní stream, which supplies water to Eldorado, economic compensation mechanisms are required for the owners of the properties that provide environmental services to society. The objective of this work is to analyze the situation of environmental and socioeconomic factors, related to the watershed of the Piray Miní stream, and to propose a scheme of payments for hydrological ecosystem services for the conservation and restoration of ecosystems. Regarding the materials and methodologies, background analyzes and interviews were carried out; and their own reflections on the subject. The survey of reference watersheds was carried out with the Geographic Information System and land inspections were carried out. As results, environmental, social and economic factors and compensation mechanisms for ecosystem services in force in Argentina were characterized; proposing the assessment and implementation of a compensation scheme for ecosystem services for the watershed of the Piray Miní stream. It is concluded that it is very necessary to implement the proposals to achieve the conservation of the properties that provide hydrological ecosystem services.

Assessing the Potential Impacts of Urban Expansion on Hydrological Ecosystem Services in a Rapidly Urbanizing Lake Basin in China

Hydrological ecosystem services (HESs) such as water purification and water supply are important for providing other ecosystem services such as drinking water, recreation, and human health. Land use change caused by urbanization is a direct driver affecting the provision of HESs. The quantification and integration of HES into watershed management and urban planning have become increasingly important. In this study, we highlighted an integration of the InVEST and CLUE-S models to simulate and predict future changes of HES in a rapidly urbanizing lake basin, namely the Nansihu Lake basin of China. The spatiotemporal patterns of HESs including water yield, water purification, and sediment export in the past five decades (from 1980 to 2015) have been revealed through our integrated modeling approach. Furthermore, urbanization and land use change scenarios till 2030 were developed using land use, topography, climate, and soil data. It is found that due to the rapid expansion of urban land, water yield, total nitrogen (TN), and total phosphorus (TP) export has increased by 5.5%, 7.38%, and 7.02%, respectively, while the sediment export has decreased by 4%. As a result, the risks of flooding and water quality degradation increased. Under a hybrid ecological and farmland redline policy (EFRP) scenario, the HESs have all been significantly improved compared to the level in 2015. This research can help to predict the future changes in HESs for land use management and ecological and environmental protection in the Nansihu Lake basin.

Use of water decision-support tools for drought management

Climate is changing in ways that may significantly affect the provision of hydrologic ecosystem services in arid or semi-arid regions. To answer this challenge, there has been an effort to increase the adaptive capacity of organizations that manage water and the land-uses water supports. Governmental and non-governmental organizations (NGOs) managing large landscapes in the United States Northern Rockies region have access to a variety of water decision-support tools, such as indicators of precipitation and snowpack, which could increase their adaptive capacity to manage hydrologic ecosystem services under changing conditions. Yet little is known about the use of decision-support tools in this region and how tools could be improved. With the aim of informing future tool development and addressing information-use gaps, we conducted semi-structured interviews with representatives of federal and state agencies and NGOs to 1) identify which tools are being used, 2) describe tool-supported management actions across different types of organizations, and 3) determine “usability” criteria managers consider when adopting a climate tool. Through qualitative analysis, we found multiple types of tools being used, including processes and frameworks, data and models, and geospatial or web-based tools. We also identified several criteria that study participants used to assess whether or not to use a tool within their organization, including tool accuracy, robustness, extendibility, interpretability, capacity, and institutional fit. This study suggests that increased communication between tool developers and end-users, with a focus on tools’ relevance and ability to support management actions, could improve tools and increase the adaptive capacity of users. This research also points to the need for multiple lines of future research including how to improve the fit between organizational goals and water tools.

Investigating potential hydrological ecosystem services in urban gardens through soil amendment experiments and hydrologic models

Among the ecosystem services provided by urban greenspace are the retention and infiltration of stormwater, which decreases urban flooding, and enhanced evapotranspiration, which helps mitigate urban heat island effects. Some types of urban greenspace, such as rain gardens and green roofs, are intentionally designed to enhance these hydrologic functions. Urban gardens, while primarily designed for food production and aesthetic benefits, may have similar hydrologic function, due to high levels of soil organic matter that promote infiltration and water holding capacity. We quantified leachate and soil moisture from experimental urban garden plots receiving various soil amendments (high and low levels of manure and municipal compost, synthetic fertilizer, and no inputs) over three years. Soil moisture varied across treatments, with highest mean levels observed in plots receiving manure compost, and lowest in plots receiving synthetic fertilizer. Soil amendment treatments explained little of the variation in weekly leachate volume, but among treatments, high municipal compost and synthetic fertilizer had lowest leachate volumes, and high and low manure compost had slightly higher mean leachate volumes. We used these data to parameterize a simple mass balance hydrologic model, focusing on high input municipal compost and no compost garden plots, as well as reference turfgrass plots. We ran the model for three growing seasons under ambient precipitation and three elevated precipitation scenarios. Garden plots received 12–16% greater total water inputs compared to turfgrass plots because of irrigation, but leachate totals were 20–30% lower for garden plots across climate scenarios, due to elevated evapotranspiration, which was 50–60% higher in garden plots. Within each climate scenario, difference between garden plots which received high levels of municipal compost and garden plots which received no additional compost were small relative to differences between garden plots and turfgrass. Taken together, these results indicate that garden soil amendments can influence water retention, and the high-water retention, infiltration, and evapotranspiration potential of garden soils relative to turfgrass indicates that hydrologic ecosystem services may be an underappreciated benefit of urban gardens.

Implications of spatial priority areas for hydrological ecosystem services through coupling hydrology model and Zonation model under different economic costs of water utilizations in northernmost of Japan

Implications of spatial priority areas for hydrological ecosystem services through coupling hydrology model and Zonation model under different economic costs of water utilizations in northernmost of Japan

Willingness to pay estimation of microhydro power plant user for hydrological ecosystem services in North Buton Wildlife Reserve Area

One of community empowerment programs implemented by the Ministry of Environment and Forestry is the construction of a Micro Hydro Power Plant (MHP) for communities around forest areas. One of the environmental services provided by forests is hydrological benefit in the form of water source to drive MHP turbines. The existence of the perceived benefit will trigger public awareness to participate in preserving forest functions. Rewards for benefits generated from forests can be manifested through efforts to conserve water resources jointly between the community and the party that manages the area. In this regard, this research is conducted to determine the willingness to pay of MHP users around the North Buton wildlife reserve to maintain the MHP unit and support forest resource conservation activities. This study employes the contingent valuation method (CVM) to calculate the willingness to pay value. The results show that MHP users are willing to pay IDR 2,611.- for each kWh of electric power. The willingness to pay is influenced by the amount of electricity consumption and the amount of income of the respondent. If it is calculated based on the volume of water used, the total willingness to pay for environmental water service is IDR 414.-per 1 liter per second.

Non-invasive methods in the identification of hydrological ecosystem services of a tropical isolated wetland (Brazilian study case)

In Brazil, since 2013 the Southeast region has been dealing with recurrent hydric stress resulted from the prolongation of the dry season, whose tendency is to be more dramatic in the function of climate change. The situation is more critical in some areas, including Cordeirópolis, projecting a reduction of 50%–100% in water availability in the next 15 years, demanding urgency in water availability-use balance. Considering the significant presence of small Geographic Isolated Wetlands (GIW) in the region, it is crucial the recognition of the link between wetlands and hydrology in the catchment since these ecosystems store rainwater and can act as aquifer recharger zones. The objective of this study is to evaluate the effectiveness of non-invasive methods, such as UAV-mapping and DC resistivity, and low-invasive (in situ hydraulic conductivity) to unveil the hydrological ecosystem services of a GIW in terms of surface and groundwater. From the high-resolution orthomosaic and digital elevation model, three compartments were qualified and quantified; (i) current wetland, (ii) Flooding area and, (iii) Potential wetland expansion. From the DC resistivity, the interaction between surface water and groundwater was identified, indicating the presence of a shallow saturated only beyond the perimeter of the current wetland as a possible result of land-use conversion or climate change. In addition, the local igneous intrusion comprises the connection between shallow/surface waters and deep aquifers made by fractures. Thus, the association of both methods showed high applicability concerning the identification of GIW superficial hydrological functions (UAV) and the system's subsurface dynamic (DC resistivity).

Impact of landscape pattern changes on hydrological ecosystem services in the Beressa watershed of the Blue Nile Basin in Ethiopia

Landscape pattern changes are mostly due to human activities, and such changes often affect ecosystem functions and services. This study was conducted to evaluate the response of hydrological ecosystem services (HESs) to structural landscape changes. Spatiotemporal changes in two specific HES indicators, water yield (WY) and sediment export (SE), were quantified by analyzing historic (1972–2017) and projected land use/land cover changes (2017–2047). The Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) Model was used for this purpose. Results indicated that WY and SE changed significantly (p ˂ 0.01) during the study period. The total WY and SE increased by 30.29% and 98.69%, respectively, between 1972 and 2017. Analysis of the projections for the next three decades (2017–2047) suggested an increase in WY and SE by 4.8% and 93.11%, respectively. Furthermore, results revealed that WY and SE are strongly influenced by landscape composition, and metrics such as percentage of landscape (PLAND), mean patch size (MPS), and large patch index (LPI) of farmland and plantations were found to be key factors affecting HESs degradation in the Beressa watershed. PLAND (VIP = 1.34; w = 0.55; and VIP = 1.32; w = 0.56) and MPS (VIP = 1.32; w = 0.50 and VIP = 1.31; w = 0.56)) of farmland cover contributed most to the changes in WY and SE, respectively. Similarly, PLAND (VIP = 1.33; w = 0.54 and VIP = 1.28; w = 0.52), LPI (VIP = 1.27; w = 0.52 and VIP = 1.30; w = 0.54) and MPS (VIP = 1.29; w = 0.52) of plantation cover also contributed more to the change in WY and SE. Besides that, of anthropogenic factors, compositions of natural vegetation and grassland cover were found to heavily influence HESs in the watershed studied. The findings of the study suggest that soil and water conservation interventions are vital to minimize and control water-related problems and enhance ESs.

Analysing the Impact of Climate Change on Hydrological Ecosystem Services in Laguna del Sauce (Uruguay) Using the SWAT Model and Remote Sensing Data

Assessing how climate change will affect hydrological ecosystem services (HES) provision is necessary for long-term planning and requires local comprehensive climate information. In this study, we used SWAT to evaluate the impacts on four HES, natural hazard protection, erosion control regulation and water supply and flow regulation for the Laguna del Sauce catchment in Uruguay. We used downscaled CMIP-5 global climate models for Representative Concentration Pathways (RCP) 2.6, 4.5 and 8.5 projections. We calibrated and validated our SWAT model for the periods 2005–2009 and 2010–2013 based on remote sensed ET data. Monthly NSE and R2 values for calibration and validation were 0.74, 0.64 and 0.79, 0.84, respectively. Our results suggest that climate change will likely negatively affect the water resources of the Laguna del Sauce catchment, especially in the RCP 8.5 scenario. In all RCP scenarios, the catchment is likely to experience a wetting trend, higher temperatures, seasonality shifts and an increase in extreme precipitation events, particularly in frequency and magnitude. This will likely affect water quality provision through runoff and sediment yield inputs, reducing the erosion control HES and likely aggravating eutrophication. Although the amount of water will increase, changes to the hydrological cycle might jeopardize the stability of freshwater supplies and HES on which many people in the south-eastern region of Uruguay depend. Despite streamflow monitoring capacities need to be enhanced to reduce the uncertainty of model results, our findings provide valuable insights for water resources planning in the study area. Hence, water management and monitoring capacities need to be enhanced to reduce the potential negative climate change impacts on HES. The methodological approach presented here, based on satellite ET data can be replicated and adapted to any other place in the world since we employed open-access software and remote sensing data for all the phases of hydrological modelling and HES provision assessment.

Effects of land-cover and watershed protection futures on sustainable groundwater management in a heavily utilized aquifer in Hawai\u2018i (USA)

Groundwater sustainability initiatives, including sustainable yield and watershed policy protection policies, are growing globally in response to increasing demand for groundwater, coupled with concerns about the effects of climate and land-cover change on groundwater supply. Improved understanding of the impacts of watershed management on groundwater yields and management costs—particularly in the broader context of climate and land-cover change—is critical to inform these initiatives and facilitate integrated land and water management. This study develops a novel, spatially explicit groundwater hydrologic ecosystem services framework, which combines stakeholder-defined land-cover scenarios, sustainable yield estimation using a groundwater simulation optimization approach, and economic valuation, and applies it in the most heavily utilized aquifer Hawai‘i (USA). Sustainable yield estimates and resulting differences in replacement costs are estimated for six land-cover scenarios (with varying levels of urban development and watershed management) crossed with two water demand scenarios in a context of a dry future climate (Representative Concentration Pathway [RCP] 8.5 mid-century). Land-cover change is found to be an important, though less significant drive of changes in groundwater recharge than climate change. The degree of watershed protection, through preventing the spread of high-water-use, invasive plant species, is projected to be a much stronger land-cover signal than urban development. Specifically, full forest protection increases sustainable yield by 7–11% (30–45 million liters per day) and substantially decreases treatment costs compared with no forest protection. Collectively, this study demonstrates the hydrologic and economic value of watershed protection in a context of a dry future climate, providing insights for integrated land and water policy and management in Hawai‘i and other regions, particularly where species invasions threaten source watersheds.

A collaborated framework to improve hydrologic ecosystem services management with sparse data in a semi-arid basin

Abstract Applying various models to assess hydrologic ecosystem services (HESs) management has the potential to encourage efficient water resources allocation. However, can a single model designed on these principles be practical to carry out hydrologic ecosystem services management for all purposes? We address this question by fully discussing the advantages of the variable infiltration capacity (VIC) model, the soil and water assessment tool (SWAT), and the integrated valuation of ecosystem services and tradeoffs (InVEST) model. The analysis is carried both qualitatively and quantitatively at the Yixunhe River basin, China, with a semi-arid climate. After integrating the advantages of each model, a collaborated framework and model selection method have been proposed and validated for optimizing the HESs management at the data sparse scenario. Our study also reveals that the VIC and SWAT model presents the better runoff reproducing ability of the hydrological cycle. Though the InVEST model has less accuracy in runoff simulation, the interannual change rate is similar to the other two models. Furthermore, the InVEST model (1.08 billion m3) has larger simulation result than the SWAT model (0.86 billion m3) for the water yield, while both models have close results for assessment of sediment losses.

Impact of Climate Change on Worlds Economy and Hydrological System

The Mediterranean region appears to be particularly responsive to global and climate change. The global mean temperature has increased by 0.8°C compared with preindustrial levels while Europe has warmed more than the global average, especially in the Mediterranean, the north-east region, and mountain areas. Increasingly drier conditions are observed in the Mediterranean region both in the wet and in the dry season (~20%) with an increasingly irregular precipitation in both seasons (~ 40% in the dry season). The annual river flows have also decreased in the Mediterranean region, a difference projected to exacerbate due to climate and global change, which made the Mediterranean region most prone to an increase in drought hazard and water stress. Iberian Peninsula has been already affected by several major droughts, e.g. the recent one in 2005. These driving forces of global change impacts on water availability, water quality, and ecosystem services in Mediterranean river basins of the Iberian Peninsula, as well as their impacts on the human society and economy, makes it an important issue on the EU agenda. This thesis is an approach to quantify and analyze the water quantity, hydrological ecosystem services, and water supply in temperate regions under environmental changes. A hydrological model is developed for a low flow Mediterranean river (Francolí River) to assess the water allocation situation in the river basin using MIKE BASIN. Since the Mediterranean regions are hard hit by the changes in the global climatic patterns, the hydrological model focuses on the water distribution system &amp; flow in the region.

Forest regeneration can positively contribute to local hydrological ecosystem services: Implications for forest landscape restoration

Abstract Governments are increasingly committing to significant forest restoration. While carbon sequestration is a major objective, the case for restoration often includes benefits to local communities. However, the impacts of forest restoration on local hydrological services (e.g. flood and erosion risk, stream flow during dry periods) are surprisingly poorly understood. Particularly limited information is available on the impacts of passive tropical forest restoration following shifting cultivation. The outcome depends on the trade‐off between the improved soil infiltration capacity (reducing overland flow and increasing soil and groundwater recharge) and greater evapotranspiration (diminishing local water availability). Using measurements from highly instrumented plots under three vegetation types in the shifting cultivation cycle in Madagascar's eastern rainforests (forest, tree fallow and degraded abandoned agricultural land), and infiltration measurements for the same vegetation types across the landscape, we explore the impacts of forest regeneration on the ecohydrological processes that underpin locally important ecosystem services. Overland flow was minimal for the tree fallow (similar to the forest) and much lower than for the degraded land, likely leading to a lower risk of erosion and flooding compared to the degraded land. Conversely, evapotranspiration losses were lower for the tree fallow than the forest, leading to a higher net recharge, likely resulting in more streamflow between rainfall events. These results demonstrate that young regenerating tropical forest vegetation can positively contribute to locally important hydrological ecosystem services. Allowing tree fallows to recover further is unlikely to further reduce the risk of overland flow but may, at least temporarily, result in less streamflow. Synthesis and applications. Encouraging natural regeneration is increasingly seen as a cost‐effective way to deliver forest landscape restoration. Our data suggest that increasing the abundance of young secondary forest in the tropics, by increasing fallow lengths in the shifting cultivation cycle, could make a positive contribution to locally important hydrological ecosystem services (specifically reducing overland flow and therefore erosion and flooding, while maintaining streamflows). Such empirical understanding is needed to inform the models used for planning forest landscape restoration to maximize benefits to local communities.

Using the Soil and Water Assessment Tool to develop a LiDAR-based index of the erosion regulation ecosystem service

Maps of ecosystem services are becoming increasingly useful for reporting on the potential impacts of human activity on the environment. However, interactions in watersheds are complex, and mapping hydrological ecosystem services (HES) requires indicators which accurately measure underlying processes. The main objective of this study was to take advantage of the Soil and Water Assessment Tool (SWAT) and Light detection and ranging (LiDAR) data to map the erosion regulation service for a managed boreal forest watershed. To do so, SWAT and partial least-squares (PLS) regression were used to select explanatory variables for sediment yield. Variables of importance in projection (VIP) with a score > 1 were selected to develop LiDAR-based ecological indicators. Four categories of variables were identified as VIP from the PLS: (i) climate: annual precipitation, (ii) land use: forest, cutovers; (iii) land use patterns: cutover patch cohesion index, and (iv) morphometric: main channel length, channel length and sub-watershed area. The height of the 95th percentile of LiDAR returns (p95) < 5 m provided the most accurate spatial representation of cutovers and the optimal cutover patch cohesion index. Other morphometrics were obtained from a LiDAR-based digital terrain model. Explanatory variables for sediment yield were combined in a sediment erosion control (SEC) index, except for yearly average precipitation because the SEC index is not actually used as a temporal index. As expected, a negative relationship was found between sediment yield and SEC index rankings for the 2006-2015 period (Spearman, rho = -0.6, p < 0.05). Moreover, the overall agreement between SWAT and SEC index classes was 87% for 31 sub-watersheds. The study provides a list of relevant explanatory variables for modelling sediment yield in a boreal forest watershed where timber harvest activities occur. It also demonstrates the use of LiDAR data for deriving an index of the erosion regulation ecosystem service in a proxy-based approach as it had not been demonstrated previously at the watershed level. The validation method applied here fills a gap in ecosystem services mapping that could benefit studies in other watershed contexts.