Millions of people residing in river basins across the world are dependent directly or indirectly on river ecosystems. Monitoring the health of a river by measuring river water quality is thus crucial. Rivers may encounter pollutants entering them due to industrial, agricultural or anthropogenic activities. To study the effects of each of these factors, it is essential to have access to data from continuous measurements. While government and non-government agencies collect data on river water quality parameters through analysis of lab samples collected in the field, there is value to gathering continuous time-stamped, geo-tagged data through in-situ measurements.
This study uses new developments in technology to build scalable, simple to use and affordable cyberphysical sensor networks across rivers in India, based on non-stationary mobile sensors for mapping river water quality as a function of space and time. This will empower researchers with data and technology to capture the quality of the river water using different parameters, in different seasons and at different locations across the rivers. Following curation of the geospatial and temporal water quality data, we apply analytic and physics based techniques to predict the spread of pollution, interpolate sparse data, and carry out inverse analysis to identify sources of pollution.
The project will demonstrate that scalable water quality mapping systems can detect and predict water contamination and thereby
High frequency special and temporal data will help governments, health experts, and other decision makers make choices for water usage based on real-time Big Data and ensure regulatory compliance. The data gathered, along with the analysis, will enable the team to evaluate the impact of various factors such as the installation of sewage treatment plants and the establishment of industries.
The overall methodology of data collection and analysis includes carrying around a submersible automated sensor on a boat at different times of the day based on a pre-defined route. This sensor is chosen to measure parameters of interest based on the kind of pollution being monitored including industrial, agricultural, anthropogenic, etc. This time stamped, geo-tagged data is then filtered and superimposed on geospatial maps to create heatmaps for ease of interpretation and analysis. Furthermore, interpolating these data points allows us to create two-dimensional area heatmaps to help with predictive analysis. This is helped by detailed lab analysis on a regular basis to support in-situ field measurements.
The chemical characteristics of natural water are a reflection of the soils and rocks with which the water has been in contact. In addition, agricultural and urban runoff along with treated wastewater from municipal and industrial outlets impacts the water quality. This is measured by several factors; including physical, chemical and biological. Parameters such as temperature, electrical conductivity, pH, dissolved oxygen and turbidity are measured using thermometric, electrometric and turbidometric techniques. These parameters are measured in-situ using the real-time data logging sensors. Microbial and chemical transformations affect the chemical characteristics of water which depend on inorganic and organic compounds. Inorganic compounds may dissociate to varying degrees, to cations and anions.
Temperature influences biochemical reactions in water bodies; temperature variability is usually due to atmospheric interactions except around thermal plants which may be responsible for temperature pollution. Electrical conductivity gives a measure of the inorganic salts in the water. pH of water states the acidic or basic nature of water. Most streams have a neutral to slightly basic pH of 6.5 to 8.5. If stream water has a pH less than 5.5, it may be too acidic for fish to survive in, while stream water with a pH greater than 8.6 may be too basic. Dissolved oxygen concentration indicates health of the water body. Dissolved oxygen ranges vary from 0 mg/L (anoxic conditions) to 19 mg/L (supersaturated) and typically ranges between 3 to 9 mg/L. Water clarity is estimated in terms of turbidity which is an optical parameter.
Major cations found in natural water include calcium, magnesium, sodium and potassium, whereas major anions include chloride, sulfate, carbonate, bicarbonate, fluoride and nitrate. Along with the major ions, heavy metals are the inorganic elements, which effect human health by causing several diseases though their levels are generally very minute.
Organic compounds in water also affect the water quality. Organic chemicals cause disagreeable tastes and odours in drinking water. Organic compounds may be formed through natural processes or synthetic ones. Dissolved oxygen levels may be depleted due to high levels of organic content in the water. To quantitatively assess concentration of organic materials, oxygen demand is used an indicator. This oxygen demand includes Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD).