Surface Water modelling using Remote Sensing. It uses curve number method

1. ARJUN GANGADHARAN
arkarjun@gmail.com
3rd year Civil Engineering
RVS Faculty of Engineering
Coimbatore

2. The Art or Technique or Science of obtaining reliable
information about the physical objects and the
environment through the process of recording,
measuring and interpreting imagery and the digital
representation of energy pattern derived from non
contact sensor system

3. Source
Object
 Satellite
Ground station

4. As you view an object, you are
actively engaged in remote sensing. A
physical quantity (light) emanates
from the object, which is a source of
radiation. The radiated light passes
over a distance, and thus is "remote"
to some extent, until it encounters
and is captured by a sensor (your
eyes). Each eye sends a signal to a
processor (your brain) which records
the data and interprets this into
information.

5. Proper management of surface
and ground water resources is an
important step against water
scarcity.
Runoff estimation based on
rainfall is the first step in water
management.
Based on United States
Department of Agriculture (USDA)
Soil Conservation Service (SCS)
Method the runoff calculation is
done.

6. The Survey of India (SOI) Topographic maps for the
demarcation of the watershed line.
The rainfall data from Meteorological Department.
The land use and land cover map prepared from
satellite imagery.
The drainage map prepared from SOI Topographic
sheet
The soil information was collected from the Soil
Survey of India

7. 1. Land cover/land use classification
2. Trend analysis
3. Ground water flow system study
4. Rainfall – runoff modelling
methods
5. Rainfall runoff-soil conservation
system-curve number method
6. Hydrogeological evaluation and
mapping
7. Hard rock terrain and lineaments
analysis
8. Thermal imagery study
9. Soil types analysis

13.  SCS-CN theory is based on the fact that direct runoff
depends on land cover, land use, soil type and antecedent
moisture conditions of surface soil. Several accompanying
tables had been developed in association with empirical
equations
 Applying SCS method on a large area, with variant
specifications, would be almost impossible if done manually.
Regarding this matter, an automated computer model is
needed to achieve desired accuracy.
 SCS rainfall runoff model, developed by United States
Department of Agriculture (USDA) provides an empirical
relationship estimating initial abstraction and runoff as a
function of soil type and landuse.

14. 1.The water balance equation is expressed by Q = P – (Ia+ F)
2.Estimation of rainfall runoff using SCS-CN
model is defined by
3.For Indian soil condition the above
relation is modified as
and
4.The SCS rainfall runoff model is modified
to include parameter – watershed area, slope,
drainage length, and land cover. The equation
for average runoff Qa is defined by

15. The Curve Number (CN)
is an index developed by
the Natural Resource
Conservation Service
(NRCS), to represent the
potential for storm water
runoff within a drainage
area.

16. The data and analysis reports can be used in modelling.
It gives a clear picture of the nature of runoff in the study area.
The study report can be made use for the feasibility studies for the
construction on reservoirs or dams.
The method can be employed in the efficiency study of the
catchment.
With results we can estimate the total volume of runoff volume the
area, which is employed in many other studies such as predicting the
flood areas during monsoon.
The water scarcity of the area can be minimized by the
construction of rain water sheds/tanks.
The suitable locations for dams and reservoirs can be obtained in
such a way that the maximum runoff volume is collected by it.
Remote sensing and GIS techniques allow such analysis to
performed in a short time, at high accuracy and low costs.

17. Thank You !
