The hydro-geochemical monitoring network in India consists of a pristine forested catchment, Mule Hole (4.1 km2), and a cultivated catchment, Berambadi (84 km2) with a sub-catchment, Maddur (7.1 km2).
Monitoring set up of the Mule Hole catchment
Check the article published in Hydrological Processes summarizing the M-TROPICS activities in the Mule Hole catchment here.
The monitoring of Mule Hole was initiated in 2003. Classical weather variables (rainfall, temperature, wind velocity and direction, air humidity and global radiation) are monitored with an automated weather station located at the Mule Hole checkpost, one km away from the catchment outlet. The stream water level is measured at the catchment outlet, which is equipped with a weir and an automatic sensor. Groundwater levels are monitored from a network of 9 piezometers. Seven are placed perpendicular to the stream flow at the outlet, and two on hillslope. Geochemical monitoring consists in chemical analysis of daily rainfall events collected manually (intensity > 5 mm), ephemeral stream collected automatically at high frequency (10 to 90 minutes interval) and groundwater collected manually on monthly basis.
Variables Monitored in the Mule Hole catchment
| Variable (unit) | Frequency | Precision | Sensor/Device | Years of use |
|---|---|---|---|---|
| Weather variables – data available here | Cimel weather station (ENERCO 407 AVKT) | 2003-15 | ||
| Rain (mm) | 1 hr | Resolution 0.5 mm, precision 2% | ||
| Air temperature (°C) | 1 hr | 0.02 °C | ||
| Air relative humidity (%) | 1 hr | 0.5% | ||
| Wind velocity (m/s) | 1 hr | 3% | ||
| Wind direction (degree) | 1 hr | 1° | ||
| Global radiation (W/m2) | 1 hr | 0.05% | ||
| Weather variables – data available here | OTT weather station (WS502 UMB) with Lambrecht rain gauge | 2015- | ||
| Rain (mm) | 15 min | Resolution 0.2 mm, precision 2% | ||
| Air temperature (°C) | 15 min | ±0.2 °C (-20 °C to 50 °C) | ||
| Air relative humidity (%) | 15 min | ±2% | ||
| Wind velocity (m/s) | 15 min | 3% | ||
| Wind direction (degree) | 15 min | 3° | ||
| Global radiation (W/m2) | 15 min | 5% | ||
| Hydrological variables – data available here | ||||
| Stream level (m) | 10 min | 1 mm | OTT Thalimedes | 2003-18 |
| Stream level (m) | 30 min | 0.5 cm | Diver datalogger (Eijkelkamp) | 2018- |
| Groundwater level (m) | monthly | 1 cm | manual (OTT KL 010) | 2003- |
| Groundwater level (m) | 15 min to 1 hr | 1 mm | OTT Thalimedes (2 to 4) | 2003-15 |
| Groundwater level (m) | 15 min to 1 hr | 0.5-2.5 cm | Diver datalogger (2 to 3) | 2015- |
| Variable (unit) | Precision | Instrument | Years of use |
|---|---|---|---|
| Electrical conductivity (µS/cm) | 1% | WTW probe (in situ) | 2003- |
| pH | 0.1 | WTW probe (in situ) | 2003- |
| Dissolved organic carbon (mg/L) | <5% | Shimadzu TOC 5000 | 2003- |
| Alkalinity (µeq/L) | 10% | Manual titration | 2003-07 |
| Alkalinity (µeq/L) | <5% | Mettler Toledo Automatic titrator DL50Gx | 2007- |
| Anions F, Cl, NO3, SO4 (µmol/L) | <5% | Dionex Ion Chromatograph DX600 | 2003-11 |
| Anions F, Cl, NO3, SO4 (µmol/L) | <5% | Metrohm Ion Chromatograph COMPACT 861 | 2012- |
| Cations Na, K, Ca, Mg (µmol/L) | <5% | Jobin-Yvon ICP-OES | 2003-12 |
| Cations Na, K, Ca, Mg (µmol/L) | <5% | Methrom Ion Chromatograph COMPACT 861 | 2012- |
| Silica (µmol/L) | 10% | Hach spectrophotometer DR/2400 | 2003-12 |
| Silica (µmol/L) | <5% | Knauer UV Visible detector 2520 | 2013- |
Monitoring set up of the Berambadi catchment
This monitoring was initiated in 2005 in the Maddur sub-catchment (7.1 km2) of Berambadi, and extended to the entire Berambadi in 2010. Weather variables are monitored since 2005 with an automated weather station located at the Maddur checkpost, close to sub-catchment outlet (data available here). The Maddur stream water level (data available here) has been recorded at the catchment outlet from 2005 to 2012 and then from 2019, with a water level automatic recorder similar to that of Mule Hole. Few groundwater levels (through bore wells) were monitored in Maddur from 2006 to 2008 with data loggers (data available here). From 2005 to 2012 the Maddur outlet was also equipped with an auto-sampler that collected at high frequency (60 to 90 minutes) the ephemeral stream storms for chemical analysis. The spatial distribution of groundwater chemical composition in the cultivated part of Maddur (half downstream) has been monitored from 2006 to 2011 (data available here).
In Berambadi, an extensive monitoring of groundwater levels (n=200) was initiated across the catchment in January 2010, on monthly basis, from the tube well network used for agriculture. Two tube wells were also equipped in 2016 with data loggers for recording groundwater levels at hourly frequency. The spatial distribution of groundwater chemical composition is determined in Berambadi since 2012 (data available here), by collecting manually and analysing 140 to 180 tube wells at each campaign. Such density allows to map groundwater level and composition at the catchment scale.
