CWC Hydro-meteorological sites

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Central Water Commission has contributed substantially in collection of hydrological data all over the country. Being the apex national body for the development of surface water resources of the country, the Central Water Commission has established a network of hydrological observation stations in all the river basins. Hydro-meteorological sites (HMS) of CWC are stations responsible for the collection of hydrological, meteorological and water quality parameters.

From some such stations the data is reported once a day while others report it on twice daily or four times a day basis. So data availability is as:

• Data for each of the observed parameter reported once in a day at 0830 hrs (daily climatic data)
• Data for each of the observed parameter reported twice a day at 0830 and 1730 hrs. (twice-daily climatic data)
• Hourly Rainfall, Temperature, Humidity and Pressure Data observed by autographic rain gauge, thermograph, hygrograph and barograph respectively and
• Hourly Sunshine duration data observed using sunshine recorder

901 HMS of CWC are present according to latest India-WRIS data. Within 901, the type of site distribution includes

• 279 G
• 160 GD
• 124 GDQ
• 31 GDS
• 229 GDSQ
• 44 GQ
• 01 Q
• 23 RF only
• 10 Snow

where G, D, S, Q, RF indicates Gauge, Discharge, Sediment , Water Quality and Rainfall.

A Site can be categorized according to the activity it is doing. Within broad category are the activities as sub category of a site.(Table 1)

Table 1: List of categories and measurement of observation stations

- Gauge-Discharge

1. Gauge-Discharge-Sediment
2. X-Section

- Temperature – Dry & Wet Bulb

1. Pressure
2. Relative Humidity
3. Wind Speed – Instantaneous & Average
4. Wind Direction
5. Pan Evaporation, and
6. Temperature of Pan Water

- Chemical

1. Biological

- Warning Level

1. Danger Level
2. FRL and HFL

The database is primarily oriented towards easy and reliable data entry options for various hydro-meteorological quality and quantity variables. It organises the data into well-defined databases using concept of relational database systems. The main features of the database are highlighted as given below.

• Organised Databases

The data pertaining to different sub-basins or offices or periods can be organised in separate databases (referred as Work areas in the database) in a well-organised and methodical way.

• Master Information

The database maintains a set of important hierarchical information on administrative and drainage boundaries and that on the offices controlling various observation stations. Adequate facility is available in the system to extend or modify this type of information. This information provides a linkage between station code and all other information generated for that station present in different tables.

• Static/semi-static Data

The database provides for the entry of necessary characteristics associated with the observation stations as static and semi static data. The data pertaining to various variables is stored under well-defined data series, which also have useful characteristics, associated with them. The data on current meters and setting of the zero of the gauge for different validity periods, cross sectional profiles etc. are also stored in an organized manner.

The database maintains a set of important information on data types, administrative and drainage boundaries and that of the owner agency and various HIS offices at which the data from an observation station is processed. A number of variables are observed with the help of hydrological and meteorological network at several locations. It is also very important to note certain key characteristics of these variables. Characteristics like description, unit and type of measurement of the variables are also maintained. It maintains information and attributes which further links to data containing tables.Four fields required for defining a data type are explained below:

• Parameter ID

Parameter identification code is a three character code used to uniquely define any parameter. No two parameters can have the same identification code and this integrity is maintained by the system automatically.This is used to extract parameter information measured in lab.

• Description

Full description of the variable is given for explaining its exact meaning. Sometimes, a variable is observed by different methods/instruments and since it is required to keep these data separately, it is desired to codify them differently.

• Units of measurement

Every parameter is characterised with the units of measurement. This is a very important characteristic of the parameter since the quantitative interpretation of every data in a series depends on the units of measurement used. For a specific data type only one unit applies. A list of commonly used units is provided by the program.

• Types of measurement

Measurement of various variables are either accumulative, instantaneous or constant in nature. An instantaneous type of observation indicates the instantaneous value of the parameter at the time of measurement. On the other hand an accumulative type of observation gives the accumulated amount of the quantity being measured since the last measurement was made. Constant type of observation are made for those quantities which change only due to some artificial or man made interventions. In other words, it can be stated that the constant type of measurement remains constant till the next measurement is made. This distinction in the type of observation is of utmost important while compiling one data series into another data series with different time intervals.

There are a few State agencies and three central agencies, which are primarily responsible for maintaining various hydrological and meteorological observation stations. All the States have one surface water and one groundwater organization as the lead agency engaged in data collection besides a few other organizations like Revenue, Agricultural, Hydro-electric and Pollution departments which have limited mandate. Central agencies like Central Water Commission, Central Ground Water Board and India Meteorological Department play a vital role in collection and dissemination of data. The hierarchical record of the information on these agencies and offices is maintained in the database.It is very essential to maintain reference of various agencies and offices that control the activities and functioning of observation stations.

Click on links for more details

1. Central Water Commission Diary, 2010. Details of Hydrological Observation Stations – Basin-Wise. CWC, New Delhi, India
2. Hydrological Observation Stations in India under CWC. 2004. Central Water Commission, New Delhi, India
3. Meteorological Data year book. 2005. Central Water Commission Narmada Basin Organisation.
4. Users Manual. SWDES Version 3.0. Central Water Commission, New Delhi, India
5. Water and related statistics. 2004. Central Water Commission, New Delhi, India
6. India WRIS Hydro Observation Info System. 2011.