Changing agricultural practices and inefficient water use are depleting water resources and reducing soil fertility in India’s Ganga Basin (known in the West as the Ganges Basin), endangering the life and livelihood of its inhabitants, and polluting the Ganga River. These changes are often attributed to human influence, but our understanding of the impacts of human activities remains fragmentary. One of the primary reasons for this limitation is the paucity of baseline data on hydrologic conditions and lack of understanding of the processes operating in the critical zone—the life-sustaining area that extends from the groundwater under Earth’s surface to the tops of the tallest trees.
More than 600 million people live in the Ganga Basin. This river basin, one of the world’s largest, has a catchment area of about 1 million square kilometers. The Indo-Gangetic Plain, formed by the Ganga and the Indus Rivers, extends over most of the northern Indian subcontinent (Figure 1). The part of the Indo-Gangetic Plain that lies in India, although it covers only 13% of India’s geographical area, is known as India’s “food basket” because it produces about 50% of the nation’s total food grains [Pal et al., 2009].
Because the Ganga Basin is so important to India, the Ministry of Earth Sciences of the government of India is supporting a research project undertaken by the Indian Institute of Technology Kanpur (IITK) to establish a critical zone observatory (CZO) called the Heterogeneous Ecosystem of an Agro Rural Terrain (HEART) of the Ganga Basin. It is the first CZO in the Ganga Basin and the second in the country after the Kabini CZO in Karnataka [Sekhar et al., 2016]. The major objective of the new observatory is to monitor various climatic, hydrologic, and geochemical parameters related to the critical zone and to understand physiochemical processes responsible for its sustenance.
The new CZO adds to the existing network of global CZOs. It provides a platform for the scientific community to predict and address foreseeable challenges in food security and clean water availability in one of the most densely populated regions in the world. Here we briefly describe the challenges faced in establishing the CZO and the data sets that are being collected in the project that may serve as baseline data.
Why the Ganga Basin?
Without sufficient local information, it is difficult to quantify the environmental consequences at local, regional, and global levels that result from the rapid adoption of hybridized seeds, fertilizers, and insecticides [Matson et al., 1997]. Thus, the government of India initiated the 10-year Namami Gange Programme in 2014 as part of the National Mission for Clean Ganga with the objectives of reducing pollution and rejuvenating the Ganga River. The CZO in this region will enhance the availability of observational data for part of the Ganga Basin. Because our study region is representative of a large part of the basin, we intend to apply these regional data to the basin scale.
The continuous usage of remote sensing data at a coarse spatial resolution, where one measurement represents a large area, does not provide accurate information for smaller areas. In this regard, the CZO data will help in downscaling satellite products like Soil Moisture Active Passive (SMAP) satellite data, which are available at 9-kilometer resolution [Entekhabi et al., 2010], and assimilating the data with ground measurements for localized and relevant information dissemination.
Overall, establishing a CZO in the Ganga Basin is a first step toward understanding hydrologic processes and recommending localized, improved agricultural practices to farmers in the area. Combining these two factors could persuade farmers to adopt more sustainable agricultural practices and reduce environmental pollution.
The HEART CZO
The IITK established the HEART CZO in August 2016 in a small watershed of the basin of the Pandu River, a tributary of the Ganga River. This watershed was chosen because it is representative of the agricultural land use in the intensively managed rural parts of the central Ganga alluvial plain in Uttar Pradesh. The main stream of the watershed, about 6 kilometers long, originates from a group of ponds near Bansathi Village and meets the Pandu River near Bani Village (Figure 2). The elevation of the watershed, according to NASA’s Shuttle Radar Topography Mission (SRTM) digital elevation model [Farr et al., 2007], ranges from 126 to 143 meters above mean sea level.
The study area has a subhumid climate and is characterized by two soil types: sandy loam and loam. The average annual maximum and minimum temperatures are 42°C and 8.6°C, respectively, and the average annual rainfall is 821.9 millimeters [Tripathi, 2009], with most of the rain falling in June through September. Drone surveys show that 92% of the land area is devoted to cropland, 3.6% is built up, 2.6% is barren land, and 1.2% is covered by water.
Instrumentation and Data Sets
An array of sensors deployed in the watershed (Figure 2) continuously monitors hydroagroclimatic variables. These monitoring networks are divided into three categories on the basis of spatial and temporal resolution of the measured data:
- spatially sparse but temporally fine data
- spatially sparse and temporally coarse data
- spatially dense and temporally fine data
Two automatic weather stations installed within the watershed upstream at the village of Bansathi and downstream at the village of Bani provide data in the first category. These relatively expensive stations measure meteorological variables (solar radiation; rainfall; temperature; humidity; wind speed and direction; atmospheric pressure; pan evaporation; and soil moisture, temperature, and heat flux) at 15-minute intervals.
Portable but expensive instruments provide data in the second category. These instruments are used for weekly or biweekly measurements of surface soil moisture, leaf area index, groundwater level in open wells, pond water levels, and discharge in the main stream during monsoons. The third data category includes low-cost sensors developed in house that use low-power wide-area network technology for real-time communication. These sensors are presently being used to collect groundwater, canal water, and pond water levels.
In addition, we have collected data on static variables like topography, soil type, and land use–land cover by remote sensing using a UAV-UX5 drone at a high spatial resolution of 20 centimeters. Data on agricultural and irrigation practices are periodically collected using farm surveys and mobile crowdsourcing.
Support from the Community
The first major hurdle in setting up the CZO was the apathy of local farmers toward government projects and their skepticism that these data would be used for their benefit. The second hurdle was preventing damage to the sensors and instruments, which were deployed in open and public spaces. To gain the indispensable support of the community in deploying these costly sensors, we organized special sessions with village elders, school teachers, and farmers to explain the benefits of the project. We emphasized that the project should be “owned” by the people and not treated as an external project.
In addition, we did several rounds of deployment of dummy instruments to reduce the sense of the unknown and satisfy residents’ curiosity. Sensors are designed so that farmers feel some connection with the sensors. For example, because the majority of the population in the study area is Hindu, we added a trident, an important Hindu symbol, to the groundwater level sensor. These small steps have helped us in changing the perception of the local population and making them stakeholders in the project. At present, all our sensors have been safely deployed for 1 year without damage.
We also involve farmers and students in our data collection efforts. Students at secondary and senior schools help us in collecting rainfall data using manual rain gauges, and farmers help in collecting soil moisture data. In the past, we organized health camps and workshops for the stakeholders. We have established a center in the study area to facilitate soil testing and disseminate agricultural extension services and weather forecasts through mobile phone messages and videos.
Ongoing Work and Expected Benefits
The CZO in the HEART of the Ganga Basin provides an opportunity to establish an understanding of how anthropogenic activities are shaping today’s environmental processes in the Indo-Gangetic Plain and how this region may respond to future changes. Currently, the observed data are intended for water balance modeling, crop water management, and water quality mapping. The outcomes will be shared with the stakeholders’ community to mitigate water mismanagement and further soil quality degradation.
Ultimately, the CZO will provide scientific evidence and decision support tools that will help shape policy and management options to meet today’s needs and to sustain the natural capital of the Ganga critical zone for future generations.