Working Groups


Within the Arkavathy basin, we find that while water quality is a matter of concern downstream (with waste water inflows from the Vrishabhavathy River), water scarcity is a major concern in the upper part – the TG Halli catchment. In the latter, it has been observed that inflows into the TG Halli reservoir have declined from its design capacity of 148 MLD to 30 MLD. The key research question is why the inflows into the TG Halli reservoir are declining. In the Arkavathy basin, the hydrology component of ACCUWa seeks to address this. We have setup a set of five hypotheses to explain this:

  1. Rainfall has declined significantly.
  2. Temperature increases have increased evapotranspiration resulting in both decreased recharge and decreased run off.
  3. Intense groundwater pumping for irrigation has induced more percolation to the deeper aquifer resulting in a loss of base flow into the Arkavathy River.
  4. Evapotranspiration has increased due to a shift in land use from rainfed agriculture to perennial plantations such as fruit orchards, coconut, arecanut and Eucalyptus.
  5. Titled the “million puddle theory”, this hypothesis states that encroachments into stream channels and expansion of check dams in the upper catchment have resulted in ponding of water at various locations. Most of this water simply evaporates or is lost through evapotranspiration from riparian vegetation.

Following this, an analysis of secondary data suggests that groundwater pumping and increased evapotranspiration from Eucalyptus plantations due to land cover change are most likely the important causes as no significant trends have been observed in rainfall and temperature over the period of decline. In order to understand the contribution of these factors, we have initiated the following studies:

  • Modelling of groundwater-surface water interactions at the TG Halli catchment scale using secondary and primary data.
  • Milli-watershed studies to obtain a detailed understanding of hydrologic partitioning under different land uses.

Land Use Trends and Drivers

False colour composite image of Arkavathy catchment (March 2012)

The main purpose of this investigation is to understand what changes in land use are affecting the hydrologic cycle in the two study basins. These include land use changes that change evapotranspiration, those that affect water storage, those that change infiltration and those that reflect increasing water use. Thus, the land use changes we are focusing on are:

  1. Expansion of built-up areas (and within that, change in population densities and fraction under industry)
  2. Change in area under irrigated agriculture
  3. Change in cropping intensities
  4. Change in area under water-demanding tree crops (such as eucalyptus plantations)
  5. Change in storage available in water bodies

We are using multiple sources of data for estimating land use changes, including village-wise statistics from the government (Census and DES), land use maps prepared by KSRSAC, and our own interpretations of historical (Landsat TM) and current (IRS LISS4) satellite images, coupled with extensive ground truth.

Water Quality

The main focus of water quality research work in the larger ACCUWa framework is to understand the linkages between sources of pollution and receiving water bodies and the impacts of polluted water sources on stakeholder outcomes which is defined in terms of livelihoods, social well-being, health issues and environmental amenities.

Vrishabhavathy River (V-River) originates in the city of Bangalore and it receives wastewater from domestic and industrial uses. The wastewater gets collected into the Byramangala tank and the highly polluted tank water is used by downstream villages for irrigation of various crops such as baby corn, mulberry and coconut.

In order to connect the linkages, the sources of pollution in the Vrishabhavathy River have been identified by studying a smaller sub catchment (Peenya sub catchment) which is highly industrialized by large, medium and small scale industrial units with varying degrees of pollution. Water quality from this sub catchment is analyzed for various parameters including heavy metals. Heavy metal load is estimated by installing a 24 hour automatic water sampler and a water level recorder at the end of the sub catchment.

The impacts of using polluted water source by downstream villages is assessed by collecting and analyzing drinking water, irrigation water, vegetables (baby corn) and milk samples from three sample villages (Chikkakuntanahalli, Bannigiri and M Gopahalli) and a control village (Mudenahalli). Based on the results obtained, a health risk assessment will be carried out and this will shed light into the overall hazard index for users exposed to the contaminants.

Institutions and Governance

The institutional component of ACCUWa seeks to understand how formal laws and rules and the political culture of water agencies and water users shapes the manner in which these agencies allocate water and manage infrastructure in the short and the long run. There are four distinct arenas in which water institutions can be examined in the study basins:

  • rural agricultural use,
  • rural domestic use,
  • urban domestic/industrial use, and
  • urban effluent disposal.

Our work initially focuses on the third and fourth arenas. Within urban use, we are focusing initially on small towns in the two river basins. We hypothesize that in small towns, management of water resources is shaped by the natural endowment of resource, physical and political proximity to capital cities, and the structure of governance in the town. Within these constraints, the agencies involved make choices regarding the type of water source to use (surface or ground water or both), supply and distribution infrastructure, operation and management, and pricing.

We are initiating a study to understand how institutional and household factors influence household water security in small towns in the Arkavathy watershed (Doddaballapur, Kanakapura, Nelamangala and Ramanagara). We aim to understand the role of institutions and its effectiveness through some of the critical outcomes:

  • Average per capita supply of water,
  • Cost of the water supply to the utilities and users,
  • Equity and fairness in distribution of water,
  • Resource sustainability (ecological) and fiscal sustainability of water supply utilities,

In addition to understanding institutional aspects in each case, we also want to observe institutional effectiveness in comparative perspective across towns and basins (with Noyyal).

Household Responses

The household responses component of the ACCUWa project covers both farm and domestic sectors and addresses the following questions:

Agriculture/Farm responses

  1. What are the drivers of crop choice and land use at the farm household level?
  2. What is the impact of crop choice and land use on water consumption in agriculture?

Domestic responses

  1. What is the impact of domestic water scarcity on communities and households, especially the marginalized?
  2. How do households respond to water scarcity?

Fieldwork was conducted to address these questions in 16 randomly sampled villages in the Arkavathy basin during November 2013-January 2015. Field research included household level questionnaire surveys on farm and domestic water management, verification of crops and irrigation sources in agricultural plots, interviews with key local informants including government officials and conducting transects and focus group discussions with farmers and residents.

The farm component of the survey focused on rainfed and groundwater dependant farm households, covering a random sample of 20% of households from both the categories in each village. In total the team covered close to 400 households in the farm survey. The domestic component focused on marginalized and non marginalized households, covering a random sample of 20% of households from both the categories in each village. In total the team covered more than 500 households in the domestic survey. GPS points of water sources and locations of different crops were marked during fieldwork and borewells identified for monitoring, feeding into the land use and hydrology components of the project.

Preliminary analysis of both the farm and domestic survey datasets is ongoing.