Inland rivers serve as the primary source of freshwater for human use and regulate hydrological and ecological cycles. They play a unique role in supporting global biodiversity, biogeochemical cycles, and human societies. River discharge integrates all hydrological processes in the upstream basin, reflecting the carrying capacity of rivers, and is the most important indicator to assess river conditions. Observing river discharge and monitoring its dynamics are critical to water resource management, ecological health, and maintaining ecological flow for biodiversity within the watershed. Traditional discharge observations primarily rely on standard hydrological gauge stations, but this approach is time-consuming and labor-intensive. The establishment and maintenance of these stations are costly, and they are mainly located in the main stems of rivers, resulting in sparse distribution and a lack of observation data for many inaccessible small to medium-sized rivers and tributaries. The challenge is using limited stations to reflect the diversity of river network attributes and the impact of human activities accu- rately and comprehensively. Therefore, discharge observation and estimation have been a focal point in hydrological research. Enhancing the capability to monitor and predict dynamic water resources is crucial to support sustainObserving river discharge from space: Challenges and opportunities Chang Huang,1,2 Yunmei Li,3 Angelica Tarpanelli,4 NingLian Wang,3 and Yun Chen5,* 1School of Geography and Tourism, Anhui Normal University, Wuhu 241002, China 2Anhui Key Laboratory of Earth Surface Processes and Regional Response in the Yangtze-Huaihe River Basin, Anhui Normal University, Wuhu 241002, China 3Shaanxi Key Laboratory of Earth Surface System and Environmental Carrying Capacity, Northwest University, Xi’an 710127, China 4National Research Council, Research Institute for Geo-Hydrological Protection, Perugia 06100, Italy 5CSIRO Environment, Canberra 2601, Australia *Correspondence: yun.chen@csiro.au Received: March 17, 2024; Accepted: May 12, 2024; Published Online: May 17, 2024; https://doi.org/10.59717/j.xinn-geo.2024.100076 © 2024 The Author(s). This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Citation: Huang C., Li Y., Tarpanelli A., et al., (2024). Observing river discharge from space: Challenges and opportunities. The Innovation Geoscience 2(2): 100076. Inland rivers serve as the primary source of freshwater for human use and regulate hydrological and ecological cycles. They play a unique role in supporting global biodiversity, biogeochemical cycles, and human societies. River discharge integrates all hydrological processes in the upstream basin, reflecting the carrying capacity of rivers, and is the most important indicator to assess river conditions. Observing river discharge and monitoring its dynamics are critical to water resource management, ecological health, and maintaining ecological flow for biodiversity within the watershed. Traditional discharge observations primarily rely on standard hydrological gauge stations, but this approach is time-consuming and labor-intensive. The establishment and maintenance of these stations are costly, and they are mainly located in the main stems of rivers, resulting in sparse distribution and a lack of observation data for many inaccessible small to medium-sized rivers and tributaries. The challenge is using limited stations to reflect the diversity of river network attributes and the impact of human activities accu- rately and comprehensively. Therefore, discharge observation and estimation have been a focal point in hydrological research. Enhancing the capability to monitor and predict dynamic water resources is crucial to support sustain- able societal development in a changing environment. It represents a major objective of the International Association of Hydrological Sciences (IAHS) Prediction in Ungauged Basins (PUB) initiative (2003-2012). It is also a key component of the Panta Rhei initiative (2013-2022). Remote sensing technology is an advanced means of Earth Observation. It possesses advantages such as multiscale, multispectral, and high efficiency. It serves as an effective supplement to traditional river discharge observa- tions. Numerous studies have emerged for estimating river discharge using remotely sensed imagery as a vital aspect of river observations. In the early stages, remote sensing estimation of river discharge was primarily conducted in basins with some discharge observation data, used to extend the temporal or spatial scales of station observations. Traditional river discharge estima- tion obtained the water area or water level of rivers at different times through remote sensing and then establishing statistical relationship models with measured discharge, or adopted remotely sensed hydraulic parameters as inputs for hydrodynamic models. They rely on substantial requirements on measured data (such as observed discharge and underwater topography) to achieve high accuracy. This limits their applications in data-scarce or less accessible regions. In recent years, to address the challenge of river discharge estimation in data-scarce basins, an increasing number of studies have focused on purely remote sensing-based methods. These methods typically require establish- ing a Satellite Gauging Reach (SGR) in specific river sections. Multiple remote sensing data, including optical and microwave imagery and altimetry, are integrated to obtain hydraulic parameters such as water surface width, water level, water surface slope, and flow velocity. Subsequently, hydraulic equa- tions or flow laws are used to estimate the discharge. For these methods, the prerequisite for successful discharge estimation through remote sensing is a higher hydraulic visibility1 of the river section, indicating the sensitivity of remote sensing to hydrological responses and hydraulic changes under varying flow conditions. Recent efforts have accelerated the diversification of approaches for estimating discharge from space due to improvements in satellite sensors, which produces a range of opportunities for this field, while also creates a series of issues and challenges.
Observing river discharge from space: Challenges and opportunities
Tarpanelli, Angelica;
2024
Abstract
Inland rivers serve as the primary source of freshwater for human use and regulate hydrological and ecological cycles. They play a unique role in supporting global biodiversity, biogeochemical cycles, and human societies. River discharge integrates all hydrological processes in the upstream basin, reflecting the carrying capacity of rivers, and is the most important indicator to assess river conditions. Observing river discharge and monitoring its dynamics are critical to water resource management, ecological health, and maintaining ecological flow for biodiversity within the watershed. Traditional discharge observations primarily rely on standard hydrological gauge stations, but this approach is time-consuming and labor-intensive. The establishment and maintenance of these stations are costly, and they are mainly located in the main stems of rivers, resulting in sparse distribution and a lack of observation data for many inaccessible small to medium-sized rivers and tributaries. The challenge is using limited stations to reflect the diversity of river network attributes and the impact of human activities accu- rately and comprehensively. Therefore, discharge observation and estimation have been a focal point in hydrological research. Enhancing the capability to monitor and predict dynamic water resources is crucial to support sustainObserving river discharge from space: Challenges and opportunities Chang Huang,1,2 Yunmei Li,3 Angelica Tarpanelli,4 NingLian Wang,3 and Yun Chen5,* 1School of Geography and Tourism, Anhui Normal University, Wuhu 241002, China 2Anhui Key Laboratory of Earth Surface Processes and Regional Response in the Yangtze-Huaihe River Basin, Anhui Normal University, Wuhu 241002, China 3Shaanxi Key Laboratory of Earth Surface System and Environmental Carrying Capacity, Northwest University, Xi’an 710127, China 4National Research Council, Research Institute for Geo-Hydrological Protection, Perugia 06100, Italy 5CSIRO Environment, Canberra 2601, Australia *Correspondence: yun.chen@csiro.au Received: March 17, 2024; Accepted: May 12, 2024; Published Online: May 17, 2024; https://doi.org/10.59717/j.xinn-geo.2024.100076 © 2024 The Author(s). This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Citation: Huang C., Li Y., Tarpanelli A., et al., (2024). Observing river discharge from space: Challenges and opportunities. The Innovation Geoscience 2(2): 100076. Inland rivers serve as the primary source of freshwater for human use and regulate hydrological and ecological cycles. They play a unique role in supporting global biodiversity, biogeochemical cycles, and human societies. River discharge integrates all hydrological processes in the upstream basin, reflecting the carrying capacity of rivers, and is the most important indicator to assess river conditions. Observing river discharge and monitoring its dynamics are critical to water resource management, ecological health, and maintaining ecological flow for biodiversity within the watershed. Traditional discharge observations primarily rely on standard hydrological gauge stations, but this approach is time-consuming and labor-intensive. The establishment and maintenance of these stations are costly, and they are mainly located in the main stems of rivers, resulting in sparse distribution and a lack of observation data for many inaccessible small to medium-sized rivers and tributaries. The challenge is using limited stations to reflect the diversity of river network attributes and the impact of human activities accu- rately and comprehensively. Therefore, discharge observation and estimation have been a focal point in hydrological research. Enhancing the capability to monitor and predict dynamic water resources is crucial to support sustain- able societal development in a changing environment. It represents a major objective of the International Association of Hydrological Sciences (IAHS) Prediction in Ungauged Basins (PUB) initiative (2003-2012). It is also a key component of the Panta Rhei initiative (2013-2022). Remote sensing technology is an advanced means of Earth Observation. It possesses advantages such as multiscale, multispectral, and high efficiency. It serves as an effective supplement to traditional river discharge observa- tions. Numerous studies have emerged for estimating river discharge using remotely sensed imagery as a vital aspect of river observations. In the early stages, remote sensing estimation of river discharge was primarily conducted in basins with some discharge observation data, used to extend the temporal or spatial scales of station observations. Traditional river discharge estima- tion obtained the water area or water level of rivers at different times through remote sensing and then establishing statistical relationship models with measured discharge, or adopted remotely sensed hydraulic parameters as inputs for hydrodynamic models. They rely on substantial requirements on measured data (such as observed discharge and underwater topography) to achieve high accuracy. This limits their applications in data-scarce or less accessible regions. In recent years, to address the challenge of river discharge estimation in data-scarce basins, an increasing number of studies have focused on purely remote sensing-based methods. These methods typically require establish- ing a Satellite Gauging Reach (SGR) in specific river sections. Multiple remote sensing data, including optical and microwave imagery and altimetry, are integrated to obtain hydraulic parameters such as water surface width, water level, water surface slope, and flow velocity. Subsequently, hydraulic equa- tions or flow laws are used to estimate the discharge. For these methods, the prerequisite for successful discharge estimation through remote sensing is a higher hydraulic visibility1 of the river section, indicating the sensitivity of remote sensing to hydrological responses and hydraulic changes under varying flow conditions. Recent efforts have accelerated the diversification of approaches for estimating discharge from space due to improvements in satellite sensors, which produces a range of opportunities for this field, while also creates a series of issues and challenges.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
