Soil Conservation Projects Research Articles

Barriers to people's participation in watershed intervention projects: perspectives of experts and local communities

ABSTRACT The present study aimed to identify and prioritize people's participation barriers (PPBs) in watershed intervention projects (WIPs), considering the perspectives of both experts and local people in the Dastgerd watershed, Iran. Thirteen important PPBs in the implementation of WIPs were identified in the study. The findings indicated that a lack of participatory guidelines, an expert-oriented decision-making process, and a deficiency in economic incentives during the implementation of WIPs constituted the most crucial PPBs. In addition, according to the two-sample Kolmogorov–Smirnov test, there is a significant difference in the perspectives of the two groups regarding the importance of 60% of PPBs. The biggest differences were observed concerning the two barriers of ‘ignoring people's benefit from the project’ and ‘lack of people consultation and attention to their suggestions’. Given the substantial impact of expert opinions on policy-making in watersheds, any misconceptions they hold regarding barriers and incentives for people's participation can lead to adverse outcomes in the planning of soil and water conservation projects. To address this issue, the establishment of think tanks and the facilitation of brainstorming sessions play a pivotal role in fostering mutual understanding, aligning the perspectives of local people and experts, and making informed decisions to overcome challenges.

Cost-effectiveness of erosion mitigation to meet water clarity targets in the Manawatū-Whanganui Region of New Zealand

Soil erosion is a significant environmental issue worldwide. It affects water quality, biodiversity, and land productivity. New Zealand government agencies and regional councils work to mitigate soil erosion through policies, management programmes, and funding for soil conservation projects. Information about cost-effectiveness is crucial for planning, targeting, and implementing erosion mitigation to achieve improvements in sediment-related water quality. While there is a good understanding of the costs of erosion mitigation measures, there is a dearth of literature on their cost-effectiveness in reducing sediment loads and improving water quality at the catchment level. In this study, we estimate the cost-effectiveness of erosion mitigation measures in meeting visual water clarity targets. The analysis utilizes the spatially explicit SedNetNZ erosion process and sediment budget modelling in the Manawatū-Whanganui Region and region-specific mitigation costs. The erosion mitigation measures considered in the analysis include afforestation, bush retirement, riparian retirement, space-planted trees, and gully tree planting. We modelled two scenarios with on-farm erosion mitigation implemented across the region from 2021 to 2100, resulting in a 48% and 60% reduction of total sediment load. We estimate the marginal costs to achieve the visual national bottom line for water clarity, as assessed by the length of waterways that meet the clarity targets. We also estimate the marginal costs of improving average water clarity, which can be linked with non-market valuation studies when conducting a cost-benefit analysis. We find that gully tree planting and space-planted trees are the most cost-effective mitigation measures and that riparian retirement is the least cost-effective. Moreover, cost-effectiveness is highly dependent on current land use and the biophysical features of the landscape. Our estimates can be used in cost-benefit analysis to plan and prioritize soil erosion mitigation at the catchment and regional levels.

Vectorized dataset of silted land formed by check dams on the Chinese Loess Plateau

Check dams on the Chinese Loess Plateau (CLP) have captured billions of tons of eroded sediment, substantially reducing sediment load in the Yellow River. However, uncertainties persist regarding the precise sediment capture and the role of these dams in Yellow River flow and sediment dynamics due to the lack of available spatial distribution datasets. We produced the first vectorized dataset of silted land formed by check dams on the CLP, combining high-resolution and easily accessible Google Earth images with object-based classification methods. The accuracy of the dataset was verified by 1947 collected test samples, and the producer’s accuracy and user’s accuracy of the dam lands were 88.9% and 99.5%, respectively. Our dataset not only provides fundamental information for accurately assessing the ecosystem service functions of check dams, but also helps to interpret current changes in sediment delivery of the Yellow River and plan future soil and water conservation projects.

Soil conservation projects and their consequences: the behavior analysis of Iranian farmers

Soil conservation projects and their consequences: the behavior analysis of Iranian farmers

Exploration on High Quality Development of Soil and Water Conservation Projects in Shaanxi Province

In order to continuously consolidate and expand the effectiveness of soil and water conservation project construction in Shaanxi Province, continuously promote the improvement of project quality and efficiency throughout the entire life cycle, and effectively promote the high-quality development of soil and water conservation projects, combined with the actual situation of Shaanxi Province, we will preliminarily explore the development pattern for the future period of time.

Ecological Restoration in the Loess Plateau, China Necessitates Targeted Management Strategy: Evidence from the Beiluo River Basin

Vegetation on the Loess Plateau, China, has continuously improved thanks to certain ecological restoration (ER) strategies, including the integrated soil conservation project that began in the late 1970s and the “Grain for Green” project that began in the 1990s. The experience of these strategies in different geomorphological regions is of great value to ER worldwide. In this study, the evolution of the land-use transition (LUT) pathway and ecosystem service value (ESV) in four geomorphological regions of the Beiluo River Basin was analyzed using geo-informatic Tupu and the equivalent factor method with data from 1975 to 2015. The results indicated that, from 1975 to 2015, the proportion of forestland in the Beiluo River basin increased by 18.27%, while the areas of shrub, grassland, cultivated land, and water decreased by 1.03%, 0.16%, 18.23%, and 0.26%, respectively. In the past 40 years, the overall ESV of the basin increased by USD 3.209 billion (54.16%). The landform, vegetation cover, LUT, and ESV analysis indicated that the main ecological functions of the loess hilly and gully (LHG), loess plateau gully (LPG), rocky mountain (RM), and terrace and plain (TP) regions are soil and water conservation (SWC), SWC and food production, regulation and food production, respectively. ER projects enhanced the main ecological function of individual regions. In detail, the transition of “cultivated land → grassland” enhanced SWC function in the LHG region, and the transition of “grassland (shrub) → forestland” enhanced the regulating services of the RM and LPG regions. Moreover, the transition of “cultivated land to grassland” did not seriously lower the food production services of the TP and LPG regions, owing to the increase in grain yield per unit area. However, there were alternating transitions between cultivated land and ecological land types, implying a game between the peasant households’ demands and the ER strategies. Conflicting demands between local households and the public necessitate precision ER strategies, including land planning, ecological compensation, training and employment for local residents, etc.

Response of temperate forest ecosystem services to rainfall: A case study in the forest nature reserves of northern China

In the context of global climate change, temperate forests in climate-sensitive areas are inevitably affected. To deepen the understanding of the impact on precipitation changes into the relationship between key ecosystem services (ESs), this study selected net primary productivity (NPP), soil conservation (SC) and water yield (WY) of temperate forest in northern China as objects, and the Spearman correlation test and redundancy analysis were applied to analyze the response of ESs relationship to precipitation gradient. The results show that precipitation is the meteorological factor with the greatest impact (contribution 21.2%, p<0.01) on ESs and their relationships in temperate forests. The 600-700 mm precipitation gradient is the key turning point in the change of ESs relationship of WY with NPP and SC. This indicates that attention should be paid to the spatial variation of the 600-700 mm precipitation region in the future warm-wet in northern China, which should be used as a dividing line of forest management and policy development. Based on the results, future restoration projects in northern temperate forest should focus on (1) in areas with less than 600-700 mm of precipitation, attention should be paid to the selection of tree species for afforestation to maintain regional water balance; (2) in areas with more than 700 mm of precipitation, soil and water conservation projects need to be planned, especially in mountainous area. The research can not only support the management of temperate forest ecosystems in northern China, but also provide reference to other forest ecosystems to cope with climate change.

Impact of Long-term Soil and Water Conservation Training for Effective Implementation of Watershed Programmes in India

Responses received from fi eld functionaries who had completed fi ve and a half months of long-term soil and water conservation training at the Indian Institute of Soil and Water Conservation during 2003–2009 were analyzed to determine training impact as well as training needs for eff ective implementation of watershed management Programmes in India. The majority of trainees (81%) had total service experience ranging from 10 to 20 years. Major responsibilities of trainees mainly involved in planning and execution of watershed and soil conservation projects. The topic of structural measures for soil and water conservation in non-arable lands received the highest mean score from trainees (2.57), followed by the application of RS and GIS, map reading, delineation, characterization of watersheds (2.38),water harvesting, storage, and recycling for irrigation planning (2.33). This study further indicates that capacity-building programmes improve not only individual knowledge but also the productivity of their working areas. This fi ndings also identifi ed that lack of appropriate literature on SWC technologies is found as a major technological constraint in order to implement watershed project more eff ectively.

Interactions between the Grain‐for‐Green Program and check dams increased vegetation carbon sequestration in the Yanhe basin, Loess Plateau

AbstractVegetation carbon sequestration, usually expressed by net primary production (NPP), is an important ecosystem service (ES) to mitigate global warming. Multiple soil and water conservation projects (SWCPs) have been implemented to restore disturbed ecosystems on the Loess Plateau (LP), as one of the most eroded areas in the world. However, responses of NPP to the conservation projects are unclear due to trade‐offs between NPP and other ESs. Herein, we quantified NPP and other key ESs (i.e., water yield, soil conservation, and crop production) and the spatio‐temporal trade‐offs among them, using RS/GIS techniques and ecosystem modelling in the Yanhe basin of the LP from 1990 to 2020. Furthermore, the structural equation model was used to quantify the impact of ecological restoration projects and programmes such as check dams, terraces, and the Grain‐for‐Green (GFG) on NPP. As shown by our results, NPP reached 457 t ha−1 in 2020, which was twice what it was in 1990. Moreover, we found increasing trade‐offs between NPP and other ESs at sub‐basin scale. Specifically, 63% of NPP changes were explained by ESs and SWCPs. The combined action of check dams and GFG can promote NPP and balance trade‐offs between NPP and other ESs, while terracing decreases NPP indirectly according to its specific soil and climate conditions. Overall, the main findings provide a better understanding of the interacting processes of multi‐projects that influence vegetation carbon sequestration and the sustainable utilization of ESs in hill and gully regions of the LP.

Effects of soil and water conservation measures on sediment delivery processes in a hilly and gully watershed

China has implemented a series of ambitious soil and water conservation (SWC) projects on the Chinese Loess Plateau, which have significantly changed the erosion, transport, and deposition of sediment. As a result, the sediment flux of the Yellow River, once the largest carrier of fluvial sediment worldwide, has been reduced by approximately 85 % in the past 60 years. However, the effects of SWC measures on erosion, transport, and deposition of sediment are still difficult to quantify, which greatly limits the further planning and adjustment of SWC measures. Here, we determined soil erosion, sediment deposition, and sediment yield at different historical stages in a 187 km2 hilly and gully watershed on the Chinese Loess Plateau using the unmanned aerial vehicle (UAV) photogrammetry technology combined with check dam surveying and hydrologic monitoring. The results show that the construction of check dams and vegetation restoration significantly reduced the soil erosion rate, from 21,144 t km−2 yr−1 at Stage-1 (1960–1969) to 13,819 ± 3,622 t km−2 yr−1 at Stage-2 (1970–1999) and further to 4,723 ± 1,278 t km−2 yr−1 at Stage-3 (2000–2018). The sediment deposition rate was estimated to be 5,989 and 2,582 ± 351 t km−2 yr−1 at Stage-2 and Stage-3, respectively. The variation in the erosion and deposition of sediment led to a significant change in the sediment delivery ratio, from 1 at Stage-1 to 0.57 at Stage-2 and 0.45 at Stage-3. Our research results provide an important reference for further SWC planning.

Changes in the characteristics of flood discharge and sediment yield in a typical watershed in the Hengduan Mountain Region, Southwest China, under extreme precipitation events

Precipitation extremes can pose adverse impacts on local and downstream society, economy, and ecosystems. Accordingly, their characteristics have attracted widespread attention in many regions, such as the world famous Hengduan Mountain Region in Southwest China, where the overall characteristics in precipitation extremes have been widely reported yet. However, the spatial heterogeneity and internal variation of precipitation extremes caused by the complicated topography were rarely reported, moreover, few studies have evaluated the effect of dynamics in precipitation extremes and soil and water conservation measures on changes in flood discharge and sediment yield. In this study, a typical watershed in the Hengduan Mountain Region, the Longchuanjiang watershed, was selected to identify the dynamics in precipitation extremes from 1965 to 2018, and the contributions of soil and water conservation measures on the characteristics in flood discharge and sediment load. The results of this study are as follows. 1) Substantial decreasing trends occurred for both flood discharge and sediment yield from the early period (1965–2008) to the later period (2009–2018) in the Longchuanjiang watershed. 2) The increase in precipitation extremes in the dry-hot valley and decrease in the mountains revealed great internal variation of the characteristics in precipitation extremes in the Longchuanjiang watershed.3) Soil and water conservation measures that were implemented in recent decades, such as terraced farmland, forest and grass plantation, ecological restoration, and small reservoirs, resulted in the significant reduction of both flood discharge and sediment yield under similar extreme precipitation events. This study highlights the discrepancy of dynamics in precipitation extremes in the dry valleys with an entire watershed in the Hengduan Mountain Region, emphasizes the risks of soil erosion in the ecologically fragile dry valley, and assesses the contribution of soil and water conservation measures on changes in characteristics of flood discharge and sediment load in the selected watershed. The study results are of great importance not only for gaining a scientific understanding of changes in precipitation extremes, flood discharge, and sediment yield but also for the objective assessment of the ecological benefits of soil and water conservation projects and deployment of suitable measures in the future.

Driving Factors of Heavy Rainfall Causing Flash Floods in the Middle Reaches of the Yellow River: A Case Study in the Wuding River Basin, China

In the context of climate change, extreme rainfall events have greatly increased the frequency and risk of flash floods in the Yellow River Basin. In this study, the heavy rainfall and flash flood processes were studied as a system. Taking the driving factors of the heavy rainfall causing the flash floods as the main focus, the key factors of the heavy rainfall causing typical flash flood processes were identified, and the driving mechanism by which the heavy rainfall caused flash floods was revealed. Through comparative analysis of the rainfall related to 13 floods with peak discharges of greater than 2000 m3/s since measurements began at Baijiachuan hydrological station, it was found that different rainfall factors played a major driving role in the different flood factors. The factor that had the largest impact on the peak discharge was the average rainfall intensity; the factor that had the largest impact on the flood volume was the rainfall duration; and the factor that had the largest impact on the sediment volume was the maximum 1 h rainfall. The ecological construction of soil and water conservation projects on the Loess Plateau has had obvious peak-cutting and sediment-reducing effects on the flood processes driven by medium- and low-intensity rainfall events, but for high-intensity flash floods, the flood-reducing and sediment-reducing effects of these projects have been smaller. Therefore, despite the background of continuous ecological improvement on the Loess Plateau, the possibility of floods with large sediment loads occurring in the middle reaches of the Yellow River still exists.

Applying Analytic Hierarchy Process for Identifying Best Management Practices in Erosion Risk Areas of Northwestern Himalayas

Despite the growing importance of soil and water conservation and watershed development projects as an approach to rural development and natural resource management, there has been relatively little research on devising site-specific best management practice (BMP) to check the soil erosion losses within permissible limits, especially in hilly regions. For a sustainable watershed management programme and implementation, site specific BMPs assume importance and hold the promise of making conservation planning and watershed management simpler and more effective. The study was attempted to develop a methodology to obtain BMPs, aiming to reduce the erosion losses in erosion risk areas of the northwestern Himalayas by employing Analytic Hierarchy Process (AHP). The AHP technique was employed to prioritise the potential technologies and select the BMP suitable for a particular land area. The prioritization of technologies was performed with four criteria viz. soil erosion resistance, cost, benefit, maintenance and environment friendliness of conservation measures. The soil erosion scenario of the study area located in the northwestern Himalayas was generated with each selected measure in a SWAT model using DEM, land use maps, a soil map and climate data of the study area. Then, the resultant erosion scenario of the conservation measures was compared and used for the AHP analysis. However, other criteria were assessed based on the judgement of a group of experts as well as farmers. In this study, four conservation measures, viz. Bench Terraces (BT), Vegetative Barrier (VB), Contour Farming (CF) and Zero Tillage + Live Mulch (ZL), were considered for BMP selection. Three scenarios, viz. experts’ judgement, farmers’ opinions and combined expert and farmer opinion, were analyzed to uncover the BMP for the different zones. The result revealed that experts and farmers unanimously preferred ZL as a BMP because of its low-cost implementation value and lower maintenance requirement while significantly controlling the erosion level as well as being environment friendly. The BT was the second most preferred technology for the study area. However, BMP was recommended for different zones having high to very severe erosion (soil loss > 10 t/ha/yr). Therefore, ZL was recommended for the areas with low altitude, whereas BT was recommended for the areas having high slopes because of its high capability for erosion control in the high slopping area. The methodology will act as a useful strategy for decision makers to prioritize the technology and recommend the best management for any region after considering suitable criteria. Future work may consider more criteria for inclusion to thus recommend the technology for a region in a more realistic way.

Operation Performance and Seepage Flow of Impervious Body in Blast-Fill Dams Using Discrete Element Method and Measured Data

As a high-efficiency and low-investment method of dam construction, blast-fill dams have been widely used in water conservancy, mining engineering, soil and water conservation, disaster prevention and other projects. Through collecting data on the main projects of the blast-fill dams, the characteristics and development trends of blast-fill dams are analyzed in detail. Meanwhile, the design requirements of impervious bodies in the initial and reinforcement stages are systematically reviewed. Subsequently, with measured data of a typical blast-fill dam, the structural characteristics of blast-fill dams after blasting and the validity of the phreatic line height after reinforcement are analyzed using the discrete element method. We conclude that an appropriate construction schedule and flexible impervious material are critical features of the impervious body for a dam with large deformation. When the dam deformation is stable, a secondary treatment should be considered for the impervious body to improve the dam safety. The design ideas for the impervious body of blast-fill dams are also applicable to other dam types with large deformation for risk reduction, such as high rockfill dams, soft-rock dams and tailings dams, and have a certain significance for reference in the treatment of landslides and confined lakes.

Barriers to participatory implementation of soil conservation projects: Perspectives and priorities

Awareness of People's Participation Barriers (PPBs) in the participatory implementation of Soil Conservation Projects (SCPs) is the prelude to promoting the levels of people's participation through relevant planning. This study aims to identify, classify, and prioritize barriers to people's participation in SCPs from the viewpoints of experts and the local community in the Vardij-Varish watershed, Iran. It also examines the agreement on the importance of PPBs in SCPs from the perspectives of both groups. In this study, 11 items were classified within the framework of demographic and planning components and related economic, social, executive, and educational-extension sub-components. PPBs were also prioritized based on Friedman's non-parametric test after confirming the validity and reliability of the questionnaire. Accordingly, ignoring people's income and centralization of decision-making power in the government organization were ranked as the most important PPBs in SCPs from the perspectives of 200 residents and 28 experts, respectively. Results indicate that the dominance of the top-down process and the lack of incentives and economic benefits are the most important PPBs. Based on the two-samples Kolmogorov-Smirnov test, the two groups had different perspectives on the importance of 64% of PPBs. In general, changing the approach from non-participatory watershed management to a participatory process and converging different perspectives through group decision-making are recommended to natural resource managers in the planning process to promote people's participation in SCPs.

The Link between Landscape Characteristics and Soil Losses Rates over a Range of Spatiotemporal Scales: Hubei Province, China.

Controlling soil erosion is beneficial to the conservation of soil resources and ecological restoration. Understanding the spatial distribution characteristics of soil erosion helps find the key areas for soil control projects and optimal scale for investing in a soil and water conservation project at the lowest cost. This study aims to answer the question of how the spatial distribution of soil erosion in Hubei Province changed between 2000 and 2020. Moreover, how do the effects of natural factors and human activities on soil erosion vary over the years? What are the differences in landscape pattern characteristics and the spatial cluster of soil erosion at multiple administrative scales? We simulated the spatial distribution of soil erosion in Hubei province from 2000 to 2020 by the Chinese Soil Loss Equation model at three administrative scales. We investigated the relationship between soil erosion and driving factors by Geodector. We explored the landscape pattern and hotspots of land at different levels of soil erosion by Fragstat and hotspot analysis. The results show that: (1) The average soil erosion rate decreased from 2000 to 2020. Soil erosion is severe in the mountainous areas of western Hubei province, while it is less severe in the central plains. (2) Land-cover type, precipitation, and normalized difference vegetation index are the most influencing factors of soil erosion in 2000–2010, 2015, and 2020, respectively. (3) The aggregation index values at the town scale are higher than those at the city and county scales, while the fractal dimension index values at the town scale are lower, which indicates that soil erosion projects are most efficient when the project unit is ‘town’. (4) At the town scale, if the hotspot area (6.84% of the total area) is treated as the protection target, it can reduce 50.42% of the total soil erosion of Hubei province. Hotspots of soil erosion overlap with high erosion zones, mainly in the northwestern, northeastern, and southwestern parts of Hubei province in 2000, while the hotspots in northwestern Hubei disappear in 2020. In conclusion, land managers in Hubei should optimize the land-use structure, soil and water conservation in slope land, and eco-engineering controls at the town scale.

Assessment of land-use and land-cover changes in Pangari watershed area (MS), India, based on the remote sensing and GIS techniques

In this paper, we focus on the assessment of land-use and land-cover change detection mapping to the effective planning and management policies of environment, land-use policy and hydrological system in the study area. In this study the soil and water conservation project has been applied during the five years and after five years what changes have been found in the land-use and land-cover classes and vegetation. In this view, this land-use and land-cover mapping is a more important role to decide the policy for watershed planning and management project in the semiarid region. In an emerging countries, fast industrialization and urbanization impose a significant threat to the natural atmosphere. The remote sensing and GIS techniques are crucial roles in the study of land-use and land-cover mapping during the years of 2007, 2014, and 2017. The main objective of this is to prepare the land-use and NDVI maps in the years of 2008, 2014 and 2017; these maps have prepared from satellite data using the supervised classification method. A normalized difference vegetation index map (NDVI) was done by using Landsat 8 and LISS-III satellite data. NDVI values play a major role in monitoring the vegetation and variation in land-use and land-cover classes. In these maps, four types of land are divided into four classes as agriculture, built-up, wasteland, and water body. The results of study show that agriculture land of 18.71% (158.24 Ha), built-up land of 0.62% (5.31 Ha), wasteland of 40.33% (341.02 Ha), and water body land of 17.39% (147 Ha) are increased. Land-use and land-cover maps and NDVI values show that agriculture land of 22.97% (194.29 Ha), 5.46% (14.59 Ha), and 0.08% (0.22 Ha) decreases during the years of 2008, 2014, and 2017. The results directly indicate that the supervised classification method has been the accurate identified feature in the land-use map classes. This classification method has been given the better accuracy (95%) from spatiotemporal satellite data. The accuracy was also tally with ground-truth and Google earth information. These results can be a very useful for the land-use policy, watershed planning, and management with natural resources, animals, and ecological systems.

The dispersion mechanism of dispersive seasonally frozen soil in western Jilin Province

A large area of soda-saline soil has developed in the seasonally frozen area of western Jilin Province, northeast China. Because of the strong dispersibility of this soil, irrigation channels and other water conservation projects are often damaged or even destroyed by erosion. In this study, grey relational analysis was used to analyze the correlation between the physicochemical properties and dispersibility of the soil and thus reveal the dispersion mechanism. Moreover, the effects of salt migration and microstructural changes on soil dispersion in the seasonally frozen area were studied via a water migration simulation experiment with samples from western Jilin Province. The high cation exchange capacity, high exchangeable sodium percentage, high pH, low organic matter content, and low clay content of the soil were the main factors contributing to soil dispersion. In addition, in winter, salt in the soil constantly moved from the lower non-frozen soil layer to the upper frozen soil layer along with water. After the frozen soil layer thawed in spring, the evaporation of water at the soil surface caused the salt to continuously migrate to the surface along with the water. As a result, the sodium ion content in the surface soil increased considerably thereby enhancing soil dispersibility. However, frost heave increased the distance between soil particles, weakened the structural connection among soil particles, and loosened the soil particles. Therefore, the seasonal freeze-thaw process in the study area promoted soil dispersion. This study has a certain theoretical significance for the construction of water conservancy projects and soil improvement.

Response of sediment discharge to soil erosion control in the middle reaches of the Yellow River

Under the background of large-scale, high-intensity, comprehensive soil erosion control, the sediment discharge of the Yellow River has undergone profound changes. The quantitative evaluation of the influences of soil and water conservation on sediment discharge is not only an inevitable requirement for the objective assessment of the ecological benefits of soil and water conservation projects, but it is also a prerequisite for gaining a scientific understanding of the causes of the drastic changes in the sediment discharge of the Yellow River. Taking the trunk stream in the Toudaoguai-Tongguan section of the middle reaches of the Yellow River and its 24 primary tributaries as the research objects, the Mann-Kendall test and the double mass curve were used to determine the spatial–temporal changes in the sediment discharge over the past 60 years. The results show the following. 1) The average annual sediment discharge in the Toudaoguai-Tongguan section decreased by 81.1% (P < 0.001) over the past 60 years, with a sudden decrease in 2000. 2) From 1956 to 2000, the Toudaoguai-Wubao section, the Wubao-Longmen section, and the Longmen-Tongguan section contributed 34.76%, 30.60%, and 34.64%, respectively, to the sediment discharge measured at Tongguan station. After 2000, the contribution rates were 11.17%, 38.93%, and 49.9%, respectively. 3) Compared with 1956–2000, the average annual sediment discharge of the primary tributaries during 2001–2016 decreased by an average of 85.61%. Marginal benefit analysis indicates that, once the degree of soil erosion control in the study area reached the critical value of 32%, the marginal sediment reduction benefits of the soil and water conservation measures approached 0. Once the degree of soil erosion control exceeded 50%, the sediment discharge in the river basin decreased to a low level. These research results provide a reference for future directions and priorities in soil erosion control planning and implementation on the Loess Plateau.

Landscape Damage Effect Impacts on Natural Environment and Recreational Benefits in Bikeway

Landscape is an important element in outdoor sports recreation. Cyclists’ perception of an environment reflects their interaction with the actual environment; they become aware of the recreation site through their primary receptive senses. As one popular bikeway in Taiwan, the landscape along Dong-Feng bikeway appeals to many cyclists. Nevertheless, the landscape was spoiled due to a soil conservation project. This study follows the theorem of planned behavior (TPB) and applies contingent behavior scenario to evaluate the recreational benefits and the damage effect of landscape. The empirical model uses travel cost method (TCM) to estimate the consumer surplus of cyclists. Under the scenario of damaged landscape, the number of trips went down 1.01 times and the recreational benefit dropped to NT$750, making the cost of damaging the landscape to NT$132 per person. The result indicates that the landscape of environment quality is crucial to cyclists, and it is important to preserve the natural environment of bike paths for developing the sport tourism sustainability.