Abstract

This study introduces a water resource assessment and optimization system aimed at improving water supply and optimizing irrigation in the hill area of southern China. Focused on addressing drought vulnerability, hill flash flood prediction, and reservoir operation optimization by integrating Geographic Information System (GIS), Building Information Modeling (BIM), hydrology and hydraulic modeling (H&H modeling), and Supervisory Control and Data Acquisition (SCADA) technologies. The system’s structure involves a GIS model for reservoir watershed identification, a BIM model for essential reservoir data integration, and hydraulic modeling for flow simulation and storage optimization. Real-time data from strategically positioned SCADA sensors contribute to a continuous simulation database, enabling real-time monitoring of flow and depth, along with spatial and temporal rainfall forecasts. During drought events, the system transforms into a decision-support tool.

The developed system was implemented in a southern Chinese village spanning 15 km^² of irrigated land with eight years of continuous precipitation records. The watershed has 22 on-stream reservoirs with varied storage volumes and irrigation demands. The project follows three phases: data collection and assessment, GIS and BIM model creation for daily operational analysis, and SCADA installation for engineering analysis. The third phase integrates a hydraulic model to predict, simulate, and optimize the irrigation system. Anticipating future progress, Genetic Algorithms and machine learning will be integrated for enhanced optimization and reduced management costs. Overall, this research embodies a comprehensive approach, merging advanced technologies and data-driven methodologies to provide practical solutions for agricultural resilience in the face of water scarcity.

Keywords: GIS; Hydrological and Hydraulic models; Irrigation; SCADA; Water resource database

Problem Statement and Background

The hill irrigation systems that support agriculture in various regions are currently facing complex challenges arising from the intersecting impacts of climate change, heightened agricultural water demand, and the escalating costs associated with maintaining watershed reservoirs. These challenges pose a significant threat to the sustainability and productivity of agricultural practices in these areas. Addressing these multifaceted issues requires a comprehensive understanding of their interdependencies and the development of integrated strategies that can ensure the continued viability of hill irrigation systems.

Climate Change Impact

Climate change has led to erratic rainfall patterns, increased temperature extremes, and altered hydrological cycles in many regions with hill irrigation systems. These changes disrupt traditional irrigation schedules and water availability, leading to difficulties in managing water resources effectively [1]. It is imperative to assess how these changing climatic conditions affect water availability for irrigation, as well as identify strategies to adapt irrigation practices to the new normal. The hydrological problems that we face in hill irrigation are

Changes in precipitation patterns: Climate change is expected to cause changes in precipitation patterns in South China, which could result in more frequent and severe droughts or floods. This could affect the availability of water resources for irrigation and lead to reduced crop yields. Typical rainfall patterns in Southern China are the summer extreme warm-sector rainfall event (MayYu), and the rain cloud with high moisture brings by the typhoon between midMay to late October yearly [2]. Because of the uneven temporal distribution of precipitation due to monsoons, the importance of watershed management in conjunction with year-round irrigation is very high [3]. However, the precipitation patterns change is not fully recognized at the hill watershed. Watershed management and irrigation management are deemed to be separate entities and practiced accordingly at present.

Increase in temperature: Higher temperatures due to climate change could increase the rate of evaporation, leading to increased water loss from irrigation systems. This could reduce the amount of water available for crops, leading to decreased yields. Increased frequency and severity of extreme weather events: Climate change is expected to increase the frequency and severity of extreme weather events, such as typhoons and heavy rainstorms [4]. These events could damage irrigation infrastructure and disrupt water distribution, leading to reduced crop yields. Furthermore, extreme weather events could also lead to soil erosion and nutrient loss, which could affect soil quality and reduce crop yields.

High Agricultural Water Demand: Rapid population growth and increased agricultural production have resulted in heightened demands for water in hill regions. The pressure to produce more food exacerbates the strain on existing water resources, often leading to unsustainable extraction from reservoirs and groundwater sources. Balancing the agricultural water demand with the available supply is crucial to prevent overexploitation and ensure equitable distribution among farmers.

Watershed Reservoir Operation and Maintenance Cost: The maintenance and management of reservoirs play a pivotal role in storing water for irrigation during dry periods. However, the costs associated with reservoir maintenance, including silt removal, dam repairs, and infrastructure upgrades, have been on the rise. These expenses can strain local budgets and hinder the efficient operation of irrigation systems. Finding cost-effective solutions for reservoir maintenance and exploring innovative funding mechanisms are essential to keep these systems functional [2]. The maintenance costs associated with irrigation structures, reservoirs, and drainage channels represent a critical challenge in ensuring the efficient and sustainable management of water resources for agricultural and environmental purposes. As these infrastructure components play a vital role in water distribution, storage, and flood control, addressing the escalating maintenance expenses requires a comprehensive understanding of the underlying issues and the development of effective, long-term solutions.

Maintenance Cost Escalation: The costs of maintaining irrigation structures, reservoirs, and drainage channels have been on the rise due to factors such as aging infrastructure, changing environmental conditions, and increased material and labor expenses. These escalating costs strain the financial resources of managing authorities and communities, potentially leading to deferred maintenance, system failures, and reduced overall efficiency.

Infrastructure Degradation and Inefficiency: Unaddressed maintenance needs can result in the deterioration of irrigation structures, reservoirs, and drainage channels, compromising their effectiveness in water storage, distribution, and flood mitigation. Structural deficiencies, such as leaks, erosion, and sediment buildup, lead to reduced water conveyance capacity and inefficient resource utilization [1]. This can ultimately lead to decreased agricultural productivity, environmental degradation, and increased vulnerability to flooding events.

Balancing Budget Constraints and System Performance: The challenge lies in striking a balance between limited budgets and the imperative to maintain functional and efficient water infrastructure. Decision-makers often face difficult choices regarding resource allocation, choosing between addressing urgent maintenance needs and investing in long-term infrastructure improvements that can enhance system resilience and reduce overall costs.

Methods and Approach

Considering these challenges, a holistic approach is required that considers the interactions between climate change, agricultural water demand, and reservoir maintenance costs. This approach should involve:

• Assessing the vulnerability of hill irrigation systems to changing climatic conditions and identifying suitable adaptation strategies.
• Developing efficient water-use practices and technologies to optimize agricultural productivity while minimizing water consumption.
• Exploring sustainable methods for watershed management and reservoir maintenance that reduce costs and ensure longterm functionality.

Addressing the issues faced by hill irrigation systems will not only safeguard agricultural livelihoods but also contribute to water resource conservation, ecological balance, and the overall resilience of communities in these regions. To monitor the water resource and develop the operation procedure for the hill irrigation, the system needs to combine the GIS integration with BIM of irrigation infrastructure, Hydrology and Hydraulic Models, with IOT that connect SCADA and automation system of hydraulic structure.

GIS

Integrating Geographic Information Systems (GIS) with hydrological model creation involves a systematic approach to gathering, processing, and analyzing spatial data for an accurate representation of hydrological processes. Beginning with data collection, various sources provide topographic, land use, soil, climate, and hydrological network data [5]. Once gathered, GIS software is employed to manage and preprocess the data. Through spatial analyses, the topography’s influence on water flow, land cover’s impact on runoff, soil characteristics affecting water movement and climate data interpolation are assessed. Additionally, the hydrological network is analyzed to understand flow paths and drainage areas. These insights are then incorporated into hydrological modeling tools, with GIS aiding in model calibration and validation. The GIS-enabled model facilitates scenario analyses, helping anticipate the effects of land use changes or climate shifts on water systems. Ultimately, the integration of GIS with hydrological modeling enhances our understanding of water movement, supporting informed decision-making for water resource management and land use planning.

Using GIS for data collection and spatial analysis in the creation of a hydrological model involves several steps to gather relevant spatial data, analyze it, and develop an accurate model of the hydrological processes in each area. Here is a step-by-step guide:

Data Collection: Gather spatial data related to the hydrological system you want to model. This could include topographic data, land use/land cover data, soil data, climate data, and hydrological network data (rivers, streams, etc.). Sources of this data might include government agencies, satellite imagery, aerial photography, and field surveys [6]. Organize and preprocess the collected data to ensure consistency and compatibility. This involves georeferencing, projection matching, and data cleaning to remove inconsistencies or errors.

Topographic Analysis: Utilize elevation data (Digital Elevation Models - DEM) to analyze topography, slope, aspect, and flow direction. These factors influence surface water flow patterns and can be crucial in hydrological modeling.

Land Use/Land Cover Analysis: Analyze land use and land cover patterns using GIS tools. Determine how different land cover types affect runoff, infiltration, and other hydrological processes.

Soil Data Integration: Integrate soil data into your GIS to understand soil characteristics such as permeability, porosity, and infiltration rates. This information helps simulate how water moves through the soil.

Climate Data Incorporation: Include historical and current climate data like precipitation and temperature. Use GIS tools to spatially interpolate weather data, creating continuous surfaces for input into your hydrological model.

Hydrological Network Analysis: Analyze the river and stream network, identifying flow paths, drainage areas, and stream order. This information is vital for simulating water flow and routing.

Spatial Analysis: Utilize GIS spatial analysis tools to calculate variables like watershed delineation, flow accumulation, and flow direction. These analyses help define the boundaries of your hydrological model and how water moves through the landscape.

Model Calibration and Validation: Develop a hydrological model based on the spatial data and analyses performed in GIS. Calibrate the model using observed data and validate it against independent datasets to ensure its accuracy.

Visualization and Reporting: Use GIS to visualize model outputs spatially. Create maps that depict variables such as runoff, groundwater levels, and flow paths. These visualizations aid in understanding and communicating the hydrological processes [7]. Utilize GIS to test different scenarios and assess the potential impact of changes in land use, climate, or other factors on the hydrological system. This helps in decision-making and planning for various scenarios.

Hydrological model: Effective management of water resources in hill watersheds demands a thorough understanding of the intricate hydrological processes that govern water availability, distribution, and utilization. Hydrological models play a pivotal role in this endeavor by providing a comprehensive framework to assess water resources through key aspects such as water budget balance, reservoir water storage, and operational strategies [8]. Hydrological models contribute to assessing water resources within the context of hill watershed management should include the following.

Water Budget Balance Assessment: Understanding the water budget balance is essential in evaluating the availability and utilization of water within a hill watershed. Hydrological models simulate the inflows and outflows of water components, including precipitation, evapotranspiration, surface runoff, groundwater recharge, and losses. By accurately quantifying these processes, the model creates a comprehensive picture of water availability over time [9]. This information is vital for identifying water surplus or deficit periods, understanding the impact of climate variability, and making informed decisions regarding water allocation for various uses.

Reservoir Water Storage Assessment: Reservoirs serve as critical storage components within hill watersheds, contributing to water supply, flood control, and energy generation. Hydrological models facilitate the assessment of reservoir water storage dynamics by considering inflows, outflows, and operational strategies. These models simulate how water accumulates during periods of excess flow and is released during times of demand or controlled discharge. By evaluating reservoir behavior under different scenarios, stakeholders can optimize water storage, anticipate reservoir capacity changes, and develop strategies to manage potential flooding or drought situations.

Reservoir Operation Strategy Evaluation: The operational management of reservoirs involves determining the most efficient release strategies to meet various demands while maintaining storage levels and minimizing conflicts. Hydrological models enable the simulation of different operational scenarios, considering variables such as water supply needs, ecological requirements, energy generation, and flood control [10]. These models help decision-makers assess the trade-offs between different uses and guide the development of operation strategies that align with sustainable watershed management goals.

In practical application, hydrological models are calibrated using historical data and validated against observed conditions to ensure accuracy. Once validated, these models can be used for scenario analysis, allowing stakeholders to assess the impacts of various interventions, such as land use changes or infrastructure development, on water availability, reservoir storage, and operational outcomes. This approach enhances decision-making by providing insights into how different management strategies affect the overall water balance and resource availability.

By integrating hydrological models into hill watershed management, stakeholders gain a deeper understanding of the complex interplay between hydrological processes, reservoir storage dynamics, and operational strategies. This holistic approach empowers decision-makers to develop informed and sustainable water resource management plans that consider the needs of agriculture, communities, ecosystems, and other stakeholders [11] (Figure 1).

 

Figure 1: GIS Spatial analysis for the watershed delineation.

Within the confines of a catchment, the interpretation of the hydrologic cycle gives rise to the concept of a hydrologic budget. The hydrologic budget involves accounting for the different transport phases of the hydrologic cycle within a catchment, all with the goal of determining their respective magnitudes [12].

∆S=P-(E+T+F+Q)

In which, ΔS = change in storage, P = precipitation, E = evaporation, T = evapotranspiration, F = infiltration to groundwater, and Q = surface runoff.

Within a given time limit, the change in water depth remaining in storage in a unit area is the difference between precipitation and the sum of soil infiltration, evaporation, evapotranspiration, and ground/surface outflow. From the water depth point of view, consider the change in storage to be the excess rainfall depth, which is Ie= ΔS.

In the hill watershed, small reservoirs are designed for irrigation needs and to diffuse provided the flood mitigation from mountain flash surface runoff. The typical size for these small reservoirs storage volume ranges between 25,000-80,000 cubic meters, and control depth from five to 15 meters high, which is based on the catchment basins water resource and the construction/ operation cost [6]. A typical hill watershed detentions inflow is dependent on the catchment hydrological condition, and outflow is dominated by types: (1) uncontrolled, (2) controlled, or (3) a combination of both. Uncontrolled outflow is not subject to operator intervention, such as an ungated overflow spillway. On the other hand, controlled outflow is subject to operator intervention, as in the case of a gated orifice or spillway. In certain instances, reservoirs are outfitted with a combination of controlled and uncontrolled outflow devices or structures [9]. In a reservoir with controlled outflow, gates are used for the purpose of regulating flow through the outlet structures. The gates are operated following established operational rules. These rules determine the relation between inflow, outflow, and reservoir storage volume, considering the daily, monthly, or seasonal downstream water demands. The latter may include the minimum ecological demanding flow requirement for water quality or fisheries management [13].

At the intersection of advanced technology and natural resource management, a SCADA (Supervisory Control and Data Acquisition) system emerges as a sophisticated amalgamation of hardware and software. Primarily designed to monitor and regulate various industrial processes and infrastructures, the application of SCADA extends notably to the complex realm of hill watershed water resource management. Within this context, a SCADA application assumes a pivotal role, meticulously overseeing the intricate collection, analysis, and control of waterrelated processes. As hill watersheds stand as pivotal regional components of water supplies, characterized by intricate terrains, shifting climatic patterns, and diverse ecosystems, the significance of effective water resource management within these contexts becomes unmistakable. The SCADA application, with its capacity to navigate this intricate landscape, emerges as a linchpin in ensuring a continuous and sustainable supply of clean water to cater to the needs of both humanity and the environment alike.

A SCADA application tailored for hill watershed water resource management brings a multitude of benefits to this intricate ecosystem [14]. By harnessing real-time data collection and analysis, such a system empowers stakeholders with the insights needed for informed decision-making. This leads to the efficient allocation of water resources, minimizing waste and ensuring a sustainable supply for both human and ecological needs. Moreover, the incorporation of alarms and alerts creates early warning systems that enable rapid responses to potential threats like floods or droughts, safeguarding communities and environments alike. The ability to remotely control water-related infrastructure adds an extra layer of flexibility and efficiency, reducing operational costs and the need for physical interventions [15]. Beyond its operational advantages, this technology plays a vital role in protecting the environment by closely monitoring the watershed’s health and supporting ecologically conscious practices.

The required equipment for this project can be mainly categorized into hydrological measurement, water quality measurement, and hydrological observation. Flow meters are primarily used to record the water volume in the selected upstream and downstream areas of the watershed. Automated observation and online recording mechanisms are employed, constituting water flow detection equipment. Amidst the rugged terrain of multiple rivers and valleys, a complex hydrological model has been developed to understand water movement, reservoir management, and watershed delineation. This model considers factors such as topography, rainfall patterns, soil types, and land use. The Da Tong Stream data is monitored using flow meters, with automatic control switches deployed at the reservoir.

Case Studying

Watershed Overview: The hydrological system encompasses the Da Tong Stream, which serves as a tributary merging into the middle reaches of the Lou Ta Stream, and subsequently converging with the Qian Tang River. Encompassing an expanse of 15.0 km², the watershed encompasses a river span of 8.49 km characterized by an average slope of 14.13%. The Da Tong Village, Da Tong Second Village, and Da Tong Third Village are sequentially traversed by the stream, accommodating a collective populace of approximately 8,000 individuals. As a result of this high population density, both the land adjoining the stream and the stream itself are characterized by a substantial ratio

of impervious surfaces, necessitating the construction of an engineered channel with three distinct sections of channel geometry. The channel’s dimensions span between 6 to 12 meters in width, with depths ranging from 1.5 to 3 meters, inclusive of freeboard provisions.

The region’s undulating terrain, featuring hills, mountains, and plains, exerts a notable influence on both the patterns of rainfall runoff and the convergence of water flow. Noteworthy for its plentiful water resources and diverse vegetation, the watershed provides an accommodating habitat for numerous organisms while simultaneously contributing to the preservation of water resources and the broader ecological environment. Crucially, the Da Tong Stream watershed functions as a pivotal water source for the urban domain of Hangzhou, fulfilling a multifaceted role encompassing irrigation, rural domestic use, and municipal water supply. Within the watershed, 22 small reservoirs are distributed, boasting an average capacity of approximately 20,000 cubic meters. Detailed information regarding the reservoirs’ attributes, including volume and elevational specifications under normal, designed, and flood conditions, is cataloged within the accompanying Table 1.

Order Number	Village Community	Name	Storage capacity (normal water level) (1000 m3)	Storage capacity (designed flood level) (1000 m3)	Storage capacity (check flood level) (1000 m3)	Reservoir Level
						Flood limited. level	Dead level	normal water level
1	Datong one village	Reservoir 1	68	85.1	92.2	159	152.52	157.67
2		Reservoir 2	65.5	80.1	86.2	132.14	126.27	131.42
3		Reservoir 3	36.3	40.7	42.4	132.66	126.55	131.70
4		Reservoir 4	10.6	11.8	12.4	145.15	139.43	144.58
5		Reservoir 5	12.6	15.4	16.7	102.46	96.78	101.93
6		Reservoir 6	10.2	11.4	12.0	118.56	112.92	118.07
7	Datong two village	Reservoir 7	34.5	43.5	47.3	98.84	92.92	98.07
8		Reservoir 8	16.8	18.9	19.8	91.09	85.34	90.49
9		Reservoir 9	27.2	30.6	32.0	124.02	118.19	123.34
10		Reservoir 10	24.2	29.2	31.5	138.72	132.30	137.45
11		Reservoir 11	13.0	15.6	16.7	111.5	100	106
12		Reservoir 12	12.8	14.5	23.2	97.5	87	91.8
13		Reservoir 13	10	13.0	14.3	103.17	97.05	102.20
14		Reservoir 14	12.3	13.6	14.2	110.01	104.35	109.50
15		Reservoir 15	24.5	27.8	29.3	105.76	100.05	105.20
16	Datong three villages	Reservoir 16	52	60.2	64.1	74.43	68.61	73.76
17		Reservoir 17	26.0	31.9	34.5	85.31	79.25	84.40
18		Reservoir 18	12.4	14.8	15.9	67.78	62.15	67.30
19		Reservoir 19	3.56	45.2	49.4	90.14	84.58	89.73
20		Reservoir 20	9.6	10.9	11.5	93.5	82	88
21		Reservoir 21	12.3	1.39	14.6	83.5	77.81	82.96
22	Guancun village	Reservoir 22	14.0	17.4	18.9	59.59	53.52	58.67

Table 1: Reservoir list of Studying watershed.

The present study is centered on the investigation of a distinctive watershed characterized by its classification as a mountain stream, characterized by abbreviated length and a notably swift flow rate. This watershed, owing to its inherent attributes, is susceptible to abrupt oscillations and inundations, particularly in response to typhoons and the prevailing “Mai-Yu” precipitation pattern. The encompassing topography, characterized by steep slopes, in conjunction with constrained reservoir capacity, necessitates the reliance on mountain ponds and reservoirs to fulfill water storage requisites [6]. Considering these complexities, the integration of the proposed model assumes paramount importance. This integration facilitates a comprehensive assessment of water resources, thereby facilitating the computation of the optimal water storage depths germane to the contiguous mountain ponds. This judicious approach serves a dual purpose: firstly, to curtail the vulnerability to flash floods precipitated by intense rainfall events; secondly, to preemptively address concerns pertaining to potential water scarcity scenarios. Through this model-driven methodology, a proactive and adaptive water management strategy can be fostered, affording resilience in the face of hydrological uncertainties (Figures 2-4).