1. Introduction:

Watershed Management involves the use of water resources of an area in such a way that the quality and quantity of water resources of the area is maintained or even improved without adversely affecting the resources of that area.

Water resources of an area involve the water bodies, drainage and ground water. Water resources can be harnessed by construction of water harvesting structures. Water bodies may be provided water from dams through pipelines and canals to keep them from drying. Such activities support agricultural activities and livestock management and hence contribute towards the overall economic betterment of the region. However, such activities should be undertaken, taking utmost care that the damage caused by them to existing resources like transport infrastructure and human habitation is minimum.

Geographical Information System (GIS) can be deployed at planning stages of such an activity to identify the regions which may derive the maximum benefits from such a project as well as those regions that might be damaged by such activities, enhancing thus, the usefulness of the project and minimizing its possible adverse impacts. Use of GIS can thus make the project more viable in an economic context and more beneficial in a social context.

2. Abstract:

Under the project, analysis for watershed management activity has been undertaken for the Sabarkantha watershed of North Gujarat.The data used is the IKONOS image of 1m*1m spatial resolution. Outputs of the project include maps showing the optimum locations for construction of water harvesting structures like checkdams, gully plugs, percolation tanks etc. in the area and the optimum routes for the construction of pipelines to carry water of river Narmada to the dams of the region and for a canal to connect the water bodies of the region. The outputs have been arrived at after a thorough analysis of several features of the geography of the region such as Land use, Drainage, Slope, Rail & Road network, Water resources etc. carried out using ArcGIS utilities such as Spatial analyst. ArcGIS has also been extensively used for the preparation and updation of some of these data layers.

A customized interface for convenient display of the input data layers and output layers has been developed using Visual Basic 6 and Arc Objects providing some of the basic display utilities available in ArcMap.

3. Genesis:

Gujarat, situated in Western part of India is one of the progressive states of the country. North Gujarat and Kutchch are relatively dry regions of Gujarat. The rainfall is meager and so with increased human habitation and other acts of development groundwater level of the area has depleted. Rivers of the area go dry in every summer making the water problem even more acute. To solve the water crisis of the region and to replenish the depleted ground water level of the region government of Gujarat recently announced an ambitious project christened ‘SUJALAM-SUFALAM’.

Main objectives of the project include:

1) Pumping ‘excess’ water from the Narmada canal into nine North Gujarat dams by laying a dozen odd pipelines each about 100 km long,

2) Building an unlined canal across all the 21 rivers in North Gujarat and

3) Building two lakh farm-ponds under the food-for-work scheme.

The present project has been inspired by the ‘SUJALAM SUFALAM’ project and intends to develop a GIS for planning the achievement of above mentioned objectives for Sabarkantha district of North Gujarat.

4. Study Area:

Sabarkantha district, situated in North Gujarat has been selected as the study area. The district has been selected considering following factors:

The area has 7 dams and several small rivulets and other water bodies providing a better scope for the utility of analysis undertaken.
The area has a well developed rail and road network and also has a varied terrain (plain as well as hilly) making the analysis sufficiently challenging.
Compared to other districts of the region, with similar characteristics, the area is smaller in size.

A brief profile of the district is as follows:

Area 7390 sq. kms

Population 1761086 (’91 census)

Literacy 59.03%

Headquarter Himmatnagar

Talukas 10

Villages 1500

Towns (over 100000 population) Himmatnagar, Shamlaji, Modasa, Khedbrahma, Idar

Sabarkantha district in shown in following figure (fig. 4.1):

INDIA

GUJARAT

SABARKANTHA

Fig. 4.1 location of Sabarkantha district

5. Main Objectives Of The Project:

The project aims at achieving the following objectives using various kinds of geographical information about Sabarkantha region.

1) To prepare Soil Irrigability, Land Irrigability and Land Capability Maps of the region.

2) To suggest optimum locations for Water Harvesting structures in the region

3) To suggest an optimum route for the construction of pipelines to carry water from Narmada river to the dams of the region

4) To suggest an optimum route for the construction of a canal to connect the rivers of the region

5) To develop a customized Visual Basic user interface for the display of results

6. Analysis Criteria:

In order to be able to achieve the above-mentioned objectives the criteria that have to be considered are listed below:

1) The Water harvesting structures should be constructed at locations where the groundwater level is not very low and the water retaining capacity of the soil is high. Their location should be such that they can benefit a large area of agricultural land. The drainage pattern of the area has also to be considered for deciding the type of structure to be constructed.

2) Pipelines should be away from human habitations to prevent the chances of damage to them. Their interference with the rail and road network should be as less as possible. Their construction in the regions having a high upward slope should be avoided as much as possible to minimize the pumping costs. The overall length of the pipeline should be as less as possible to minimize the construction cost.

3) For the canal to be constructed, all the above points for pipelines are to be considered. In addition, the canal should be routed such that it can benefit a large area of irrigable land. Thus, the route of pipelines and canals should be optimum in terms of utility as well as cost.

7. Data Layers Involved:

Based on above mentioned criteria, the project involves the use of following data layers for analysis purpose:

1) Land use and Land cover

This layer represents the broad type of activity for which a given area of land is used. The main categories include agriculture, settlements, Urban areas, water bodies, forests, Open area etc.

2) Drainage map

This layer represents the manner in which the waters of an area flow off in surface streams or subsurface conduits. This is useful to know the flow strength and flow direction in the areas of interest.

3) Contour map

Contours are lines of same altitude. This layer is used to derive the slope map of the region.

4) Rail network

This layer represents the layout of railway lines in the region.

5) Road network

This layer represents the layout of national highways, state highways, primary roads, secondary roads and other roads for the region.

6) Waterbodies

This layer represents the water bodies in the region, which include Sabarmati river and other small rivulets, ponds, lakes etc.

7) Soil map

This layer represents the various characteristics of the soil in different areas of the study region. These characteristics include texture, depth, permeability, salt affected, salinity and groundwater level.

8. Methodology:

The project has been divided into three main parts:

1) Data acquisition

2) Data Analysis

3) VB user interface development

8.1 Data Acquisition:

Some of the data layers like rail network, road network, drainage and contours were available and have been used directly. Some of these layers have been extracted from the IKONOS image, which is having a spatial resolution of 1 m * 1m. Waterbody layer has been used after necessary updation using satellite image of the region. Layers such as Soil map, soil irrigability, land use, land irrigability, land capability and slope have been derived from the existing layers using some information available of the region.

Land use layer has been derived using the satellite image of the region as the basis. The land in the region has been broadly classified into only 5 important categories for the convenience of analysis. These categories include agriculture, waterbody, forest, open area, higher urban area and lower urban area.

Soil map layer has been derived using the available information about soil distribution in Gujarat. Geographical characteristics and land use type of different regions of the study area has been considered while assigning values to soil attributes.

Slope map has been derived from contour layer using ArcINFO tools such as createtin, tinarc etc.

Soil irrigability and Land irrigability maps, which represent the suitability of land for type of irrigation depending on the soil type, slope, permeability and other factors are useful for deciding or suggesting changes in the crop pattern of a region. Land capability map which represents the suitability of land for different usages such as agriculture, settlement etc. is useful for making suggestions during the planning of any area development project in the region. For analysis, these layers were required. They were derived from the available data layers according to certain criteria as described below:

Soil irrigability layer represents the suitability of soil in an area for irrigation. This layer is arrived at after considering the appropriate properties of soil. Soil is divided into five classes – from A to E with decreasing suitability for irrigation in that order. Following table has been used for deciding the soil irrigability class of any particular region.

Soil Properties	Irrigable soil classes				Non-irrigable soil classes
Soil Properties	Class A	Class B	Class C	Class D	Class E
Effective Soil Depth (Useful for crops)	> 100cm	50-100 cm	25-50 cm	10-25 cm	<10 cm
Texture of Surface (30 cm)	Sandy loam to clay loam	Loamy sand/ clay	Sand/ clay	Sand/ clay	Any texture
Soil permeability (of least permeable layer)	5-50 mm/hr	50-130 mm/hr	130-250 mm/ hr	> 250 mm/hr	Not applicable
Available water capacity (%) to depth of 90 cm	12 or more	9-12	6-9	2-6	Less than 2
Coarse fragments (%) pebbles and stones (75 mm)	Less than 5	5-15	15-35	35-65	More than 65
Gravel and kankar (25-60 mm)	Less than 15	15-35	35-55	55-70	More than 70
Rockout crops (distance apart in meters)	40	20	15	5	Less than 5
Salinity (in saturation extract	Less than 4 mmhos	4-8 mmhos	8-12 mmhos	12-16 mmhos	More than 16 mmhos
Salt affected (visual) %age of area affected	Less than 20 %	< 20%	<20%	20-50	More than 50
Severity of alkali problem	ESP less than 15 %	< 15%	<15%	ESP more than 15%	ESP>15%
Sub-soil or Substrata drainage characteristics	Lower sub-soil is at least moderately permeable or permeable layer of at least thickness occurs below the soil but within 10(sand, gravel)			No moderate permeable sub-soil or other permeable layer occurs within depth of 10
Soil erosion status	Effects of sheet and rill erosion are reflected in effective soil depth available moisture holding capacity and in some other factors shown above. Moderately or severely gullied soil may be classified based on local experience

Table 8.1.1 Soil Irrigability classes

* Only effective soil depth, soil texture, soil permeability and salinity have been considered

Land Irrigability layer represents the suitability of a particular area for irrigation. This layer is arrived at by considering the Soil Irrigability and Slope maps of the region. The land is classified in to six classes – from 1 to 6 with decreasing suitability for irrigation in that order. Following table has been used for deciding the land irrigability class for any particular region.

No.	Land characteristics	Irrigable Land classes
No.	Land characteristics	Class 1	Class 2	Class 3	Class 4	Class 5	Class 6
1	Soil irrigability class	A	A to B	A to C	A to D	A to D	D
2	Slope (%)	Less than 1	1-3	3-5	5-10	1-10	> 10
3	Drainage	Well drained	Moderately well drained	Imperfectly drained	Imperfectly drained	Imperfectly drained	Imperfectly drained
4	Ground water table (meters)	More than 3.0 meters	2-3 meters	1-2 meters	0.5-1.0 meters	Less than 0.5 meters	----

Table 8.1.2 Land Irrigability classes

* Only soil irrigability class and slope have been considered

Land capability layer represents the suitability of land for different activities like agriculture, settlements, pasture etc. The land has been classified into 8 classes – from I to VIII, considering appropriate properties of soil as well as slope. Fields with (*) mark in the following table have been used for deciding the land capability class for any particular region.

Class	Texture	Soil depth cm	%age slope			Erosion class		Permeability mm/hr	Climate
Class	Texture	Soil depth cm	Alluvial soils	Black soils	Red soils	Effect of past erosion	Susceptibility to erosion by distance from active gully heads	Permeability mm/hr	Climate
I	Ls-sl, Cl, Sicl, Sil, Scl	>100 cm	0-1(A)	0-1(A)	0-1(A)	None to slight erosion (e1)	Very far (60m)	Moderate (20-62.5)	Humid with distributed rainfall throughout
II	Sl, Scl, Cl, Sicl,Sil	50-100 cm	1-3(B)	1-3(B)	1-3(B) 3-5(C)	None to slight erosion (e1)	Minimum 60m	Moderate slow (5-20) Mod. rapid (62.5-125)	Humid with occasional dry spell
III	Sc, Sic, C, Ls	25-50 cm	3-5 (C) 5-10(D)	3-5(C)	5-10(D) 10-15(E)	Moderate erosion (e2)	Between 6-60m	Slow 1.25-5	Sub-humid fields
IV	C, S	10-25 cm	10-15(E)	5-10(E)	10-15(E) 15-25(F) 25-33(G)	Severe erosion (e3)	< 6m	V slow (<1.25) V rapid (>25)	Semi arid
V	Same characteristics as class I and expect some limitations of wetness or stoniness or rockiness or adverse climatic conditions. It has no erosion like class I land.
VI	---	10 or less	15-25(F)	10-15(E)	25-33(G) 33-50(H)	Gullied land and sand dunes (e4)	Marginal land (6m wide strip near gully head)	-----	Arid
VII	---	10 or less	25-33(G)	15-25(F)	33-50(H) 50-100(I)	Gullied land and sand dunes (e4)	Gully sides as beds	-----	----
VIII	----	Rock	>33(H)	>25(G)	>50(I) >100(J)	Bad lands	Gully sides and beds	-----	----

Table 8.1.1 Land Capability classes

* Only land irrigability class, texture, soil depth and %age slope have been considered

8.2 Analysis Part:

The analysis part involved the identification of optimum location for water harvesting structures and routes for Pipelines and Canal.

8.2.1 Water Harvesting structures:

Water Harvesting structures are very useful for replenishment of groundwater and are also helpful in supporting irrigation on a small scale. Their benefits can be maximized if important criteria like ground water level, slope, drainage etc. are taken into consideration for their construction. Water harvesting structures considered are checkdams, gull plugs and percolation tanks.

Checkdams are small earthen or masonry barriers placed across streams or nallahs that capture water as it flows downstream. The pressure created by the impounded water helps to improve infiltration and raise the local groundwater table. Full wells, along with the availability of the surface water for irrigation, benefit farmers and communities living around the checkdam long after the monsoon rains have ended.

Gully plug is a small conservation structure across small gullies and streams in hilly areas to slow the run-off of the flowing water. Gullies are formed due to erosion of top soil by the flow of rain water. In course of time, a gully assumes a big shape and erosion goes on increasing. To prevent erosion, barriers or plugs of different types of material are put across the gully, at certain intervals. It plays an important role in soil and water conservation, when many of them are put in series one below the other from top to bottom of the depression.

Percolation tanks are conservation structures aimed at inducing maximum percolation of harvested rain water.

For water harvesting structures the layers considered were Slope, Drainage, Landuse, Rail and Road network.

Following table was used for primary identification for sites for water harvesting structures:

S. No.	DRAINAGE	SLOPE	LANDUSE/ LANDCOVER	RECOMMENDATION
1	1^st, 2^nd, 3^rd order streams	0-10%	Downstream agriculture farming	Checkdam
2	1^st, 2^nd order streams	>10%	Downstream agriculture farming	Gullyplug
3	3^rd order streams	<3%	Downstream agriculture farming	Percolation tank at intersection of lineaments and drainage

Table 8.2.1 Water harvesting structures suitability criteria

After the primary locations were identified, landuse, rail and road network layers were used to arrive at the final location so that the structures would be at locations were they would be able to benefit a large area of agricultural land as well as cause minimum hindrance.

8.2.2 Canals and Pipelines:

Excess water of Narmada if carried to the dams of the region through pipelines can benefit the agriculture of the region greatly during the dry season. Similarly, if the waterbodies of the region are connected through a canal, I t may prevent or at least delay their drying up during waterless part of the year and thus support the agriculture in the region. The cost of construction of the pipelines and canal and the possible damage that may occur to the environment by its construction can be minimized by taking into consideration appropriate factors like settlement and agriculture areas, transportation network etc. for deciding the route of the pipelines.

Least cost path for canal and pipeline were arrived at using the ArcGIS Spatial Analyst tool.

The layers considered for assigning the weights were Slope, Landuse, Land capability, Rail and Road network. These layers were converted to raster data and were reclassified on a scale of 1-10. Reclassification was such that higher slopes were to be avoided and in case of road network care was to be taken to minimize the interference to national highway passing through the region. Landuse and Land capability layers carried different weights for canal and for pipelines.

These reclassified rasters were then combined with appropriate weight using Raster Calculator to form a single cost raster.

Using the cost raster cost distance and cost direction rasters were obtained for the source using cost-weighted function of Spatial Analyst. These were then used to find the least cost path from the distance to source using the shortest path function of ArcGIS Spatial Analyst.

8.3 User Interface Part:

8.3.1 Description:

A user interface has been developed using VISUAL BASIC 6 and ARCObjects library. ESRI Mapcontrol is the main component on which the interface has been developed. The component comes with several important methods and attributes which conveniently allow one to handle map display programmatically. The interface has been provided with basic display tools like pan, zoom, full extent etc. In addition other ARCMAP utilities like identify, find in layers, layer display properties, label layers etc. have also been provided.

A brief description of the utilities provided by the interface along with screenshots is given below:

Fig. 8.3.1 Main Page

1) Add/ Remove layers

Shapefiles can be selected using a common dialog control box and added to the application as layers run-time. Added layers can also be hidden or removed any time.

Fig. 8.3.2 Add layer

Fig. 8.3.3 Remove layer

2) Map display

Display of layers can be changed as per convenience using the Pan, Zoom In, Zoom Out, Fixed extent, Previous extent and next extent tools.

Fig. 8.3.4 Zoom In

Fig. 8.3.5 Zoom Out

Fig. 8.3.6 Pan

3) Layer properties

Layer display and symbology properties can be changed by the user once the layer has been added.

Fig. 8.3.7 Layer Properties

4) Identify

Identify tool can be used to know the attributes of any feature in the active layer.

Fig. 8.3.8 Identify

5) Find

Feature(s) on a particular layer can be selected by building an appropriate SQL expression using the ‘Find’ window

Fig. 8.3.9 Find in Layer

6) Label

A layer can be labeled with values of any particular attribute lf the layer as selected by the user. Labels can also be hidden when required.

Fig. 8.3.10 Label

8.3.2 Methodology:

VB has been used as the language of development due to the special ESRI libraries available for development as well as due to prior experience of work. ESRI OBJECT library and ESRI ARCMAP OBJECT library has been used. Mapcontrol is the most important component of the interface as it, along with ARCOBJECT 8.1 control allows convenient handling of Map display programmatically. Other components that have been used include Microsoft windows common control, Common dialog control and MsFlexgrid control for specific utilities like toolbar, shapefiles browsing and data display respectively.

9. Future scope:

As a part of the project soil irrigability, land irrigability and land capability maps have been prepared for the region. These maps can be used to suggest changes in the crop pattern of the region in order to maximize farm output and optimise the water usage. They can also be used for decision making during area development projects in the region. This will help to avoid the misuse of land resources and damage to environment by any development activity and will also maximize the benefit of such activities.

However, the results can be much more useful if the accuracy of the data used is improved and data layers which were not available are prepared. With accurate data layers and a more sophisticated analysis considering all criteria as well as ground reality the analysis can be carried out in all the areas to be covered by Sujalam Sufalam project and can be used for decision making in actual projects. The pipeline and canal module of the project can also be extended for the river linking project to be tentatively undertaken by government of India.

10. Conclusion:

Under the project, locations have been identified for the construction of water harvesting structures and the route for canal and pipeline has been identified. However, due to limitations of data and its accuracy the results might at some places contradict with the ground reality. Hence actual verification of identified locations is essential.

GIS has proven utilities in several other applications and should be extensively used for planning of major projects to be able to extract maximum benefits from the project at a lesser cost and in a more systematic manner.

11. Acknowledgement:

The project has been an excellent learning experience in a field which has a tremendous potential to emerge as an inevitable tool for planning of large scale projects undertaken by governments, enterprises and other institutions. It has really been of a great benefit to have an opportunity to work on such an important and socially relevant project as my first assignment in the field of GIS. I extend my hearty gratitude to my college authorities for arranging the summer training. I thank Mr. K.M Jagdeesh, as a representative of Reliance digital world pvt. Ltd., for having made this training possible and for the resources provided. I personally thank Mr. Jagdeesh for his valuable words of advice and motivation. I owe my allegiance to Mr. Sanganabasayya Ganachari for his excellent guidance and co-operation throughout the project which actually made the project possible. I also thank Mr. Deepak, Mr. Gajendiran and Mr. Unni for the brief discussions I had with them in context of my project. Finally, I extend my gratefulness to my colleagues who have been very co-operative, supportive as well as critical, thereby making my work and my days memorable.