Micro-Watershed Data Analysis Report

Overview of Tehsil characteristics

The Tehsil godda having total area 65,278 hectares has towns and cities of Godda.

Landscape Overview

The micro-watershed 12_308006 is in Tehsil godda, which has towns and cities of Godda.

Terrain Comparison

The micro-watershed is spread across 935.35 hectares. The micro-watershed mainly consists of flat plains covering 91.26 % micro-watershed area.

Note: We used NASA's SRTM Digital Elevation Model at 30m resolution to generate landform classification.

Terrain Comparison for Block and MWS

The microwatershed profile is similar to the typical microwatershed profile observed at the Tehsil level.

The chart illustrates the distribution of different terrain types across the total block. It highlights the percentage of each terrain type to the total block while also showcasing the specific percentage of a single MWS to the overall percentage.

Land use on slopes and plains

During 2017- 22, the micro-watershed's slopes and plains have exhibited distinct land-use patterns. On the plains, land use has predominance of 76.9 % farmlands, 0.05 % barren areas, and 6.48 % shrubs.

Note: Data remotely sensed from satellites including LandSat-7, LandSat-8, Sentinel-2, Sentinel-1, MODIS and Dynamic World.

Degradation

Degradation of land

There has been a considerate level of degradation of farmlands in this micro watershed over the years 2017-2022. As compared to average degraded land area of 25.0 hectares per microwater-shed for the entire tehsil, the degraded land area in this micro-watershed is close to 47.7 hectares.

Note: The degradation in cropping is computed using the IndiaSAT Land Use Land Cover outputs. Transitions from farmland to barren land, shrubs, human settlements (built-up) are computed

Reduction in Tree-Cover

There has been a considerate level of reduction in tree cover in this micro watershed over the years 2017-2022, about 16.7 hectares, as compared to 33.5 hectares on average per micro watershed in the entire tehsil.

Note: The reduction in tree cover is computed using the IndiaSAT Land Use Land Cover outputs. Transitions from tree cover to barren land, shrubs, human settlements (built-up) or farmland are computed.

4.82 hectares of this microwatershed has less than 40% canopy density and requires wide scale restoration interventions.

Cropping Intensity

The cropping intensity of this area shows no definite trend. The average cropping intensity over the years is 1.33, less than the average cropping intensity of 1.47 across the micro watersheds in the Tehsil. It might be possible to improve cropping intensity through more strategic placement, while keeping equity in mind, of rainwater harvesting or groundwater recharge structures.

Note: We use annual land use land cover (LULC), to identify areas under single cropping, double cropping and triple cropping using pixels which are classified as single kharif, single non-kharif, double and triple classes of LULC classifier to determine cropping intensity. The data used is from 2017 to 2024.

Average percentage of double cropped area

This microwatershed area has a high percentage of double-cropped land (419.28 hectares), which is more than 60% of the total agricultural land being cultivated twice a year.

Note: The Resolution of LULC image is 10 meter. The data used is from 2017 to 2024.

Surface Water Availability

The surface water availability shows no definite trend over the years 2017 to 2023.

Note: We use Sentinel-1 (SAR data) VV band for water pixel detection in Kharif season and Dynamic World to detect water pixels in Rabi and Zaid seasons.

In non-drought years, surface water in kharif typically decreases by 10.4% in rabi.

Water Balance

A water balance study of the microwatershed indicates whether it is helping conserve water or deplete water from the underlying aquifer. Incoming water into a microwatershed is predominantly through rainfall. Some of this is lost as runoff while the rest percolates into the ground. Crops pull some of this groundwater, and borewells for irrigation may pull groundwater from deeper aquifers too. A positive water balance indicates that less of the incoming water is lost, while a negative water balance indicates that the microwatershed takes away more water.

The water balance is positive and indicates that the groundwater situation in this microwatershed may be stable. Year on year, the groundwater situation seems to be improving.

In the micro-watershed, 2017, 2018, 2019, 2020, 2021, 2022, 2023 and 2024 were good rainfall years,bringing an average annual rainfall of approximately 1019.25 mm with monsoon onset between [05-28, 05-29].This rainfall pattern resulted in positive groundwater recharge, with average groundwater change of 211.2 mm, indicating replenishment of groundwater resources. During these years, around 18.16 % of the rainfall became surface runoff, offering potential for water harvesting, although this should be evaluated carefully so as to not impact downstream micro-watersheds.

Do note that currently we only consider the vertical flux in the microwatershed. We are working on how to model incoming runoff into the microwatershed, as well as sub-surface flow from adjacent areas.

Note: Precipitation data is calculated from the Global Satellite Mapping of Precipitation (GSMaP) dataset available on Google Earth Engine's data catalogue. GSMaP provides a global precipitation in mm/hr at spatial resolution of approximately 11km. Runoff is calculated using precipitation data (GSMaP at 11 km resolution), soil type (HYSOGs250m dataset), slope (NASA SRTM DEM dataset at 30 m resolution) and land cover (Dynamic World dataset at 10m resolution). For further information on the computation, refer our technical manual.

Note: Computed by subtracting outgoing fluxes (runoff and evaporatranspiration) from incoming water (precipitation).

Drought Analysis

Refer to the following graph and see how the intensity of drought has changed in this microwatershed over the years

A Drought year is declared if the total number of weeks under severe intensity drought and moderate intensity drought equal or exceeds 5, which means that the rainfall deficit was more than 25% for more than 5 weeks during the monsoon of that year.

The occurrence of dry spell is defined across four consecutive weeks with each week of these four weeks incurring a rainfall deviation of less than 50%. Prolonged dry spells can lead to significant reduction in crop sown area.

Note: Drought is defined as per the Government of India's Drought Manual and considered moderate or severe if the number of weeks of drought is five or more. Drought weeks are identified based on whether meteorological drought occurred in that week (i.e. the rains were less than usual in that week as compared to previous years, possibly intensified by dry spells defined as consecutive weeks of low rainfall) and/or agricultural drought occurred in that week (i.e. cropped area or crop health were lower than usual in that week as compared to previous years). Severe drought weeks are those when meteorological and agricultural drought are both coincident.