Groundwater Atlas — CGWB¶

Provider

CGWB (Central Ground Water Board)

Website

cgwb.gov.in

Access Level

🟢 No Login for Reports and Block Assessment

Formats Available

PDF Reports, Excel tables, limited GIS layers

Coverage

National → Block Level (all ~6,500 blocks assessed)

Key Publication

Dynamic GW Resources Assessment 2022

What CGWB Provides¶

Dataset	Description	Access
National Groundwater Map	Aquifer types, hydrogeology map of India	🟢 PDF
Dynamic GW Resources 2022	Block-wise classification (Safe/Semi-critical/Critical/Over-exploited)	🟢 Excel
Groundwater Yearbooks	State-wise depth to water table (pre/post-monsoon)	🟢 PDF
Groundwater Quality Atlas	District-wise water quality (fluoride, arsenic, nitrate, salinity)	🟢 PDF
NAQUIM (Aquifer Mapping)	Detailed aquifer maps for selected states	🟡 Portal

The Key Finding: Groundwater Crisis¶

India's Groundwater Emergency

CGWB's 2022 assessment classified:

Category	Blocks	% of Total
Over-Exploited	1,006	15.5%
Critical	260	4.0%
Semi-Critical	1,012	15.6%
Safe	3,693	56.9%
Saline	198	3.1%

Over-exploited = extraction > recharge. Punjab, Haryana, Rajasthan, and parts of Tamil Nadu and Karnataka are severely affected.

How to Access¶

Block Classification Data 🟢¶

Go to cgwb.gov.in
Click "Ground Water Data" → "Dynamic Ground Water Resources"
Download the 2022 assessment Excel — lists every block with its category
Also available on data.gov.in: search "groundwater assessment block"

Groundwater Monitoring Wells (Depth Data) 🟡¶

cgwb.gov.in → "Ground Water Data" → "State Reports"
Download Groundwater Yearbook for your state
Contains: pre-monsoon (May) and post-monsoon (November) depth to water table for all monitoring wells

Python: Map Over-Exploited Blocks¶

import pandas as pd
import geopandas as gpd
import matplotlib.pyplot as plt
from matplotlib.colors import ListedColormap

# Load CGWB 2022 block assessment (download from cgwb.gov.in)
cgwb = pd.read_excel("gw_assessment_2022.xlsx", sheet_name="Block_Data")

# Classification mapping
status_colors = {
    'OVER EXPLOITED': '#d73027',
    'CRITICAL': '#fc8d59',
    'SEMI-CRITICAL': '#fee090',
    'SAFE': '#91bfdb',
    'SALINE': '#e0e0e0'
}

# Count by state
state_summary = cgwb.groupby(['State', 'Category'])['Block'].count().reset_index()
state_summary = state_summary.pivot(index='State', columns='Category', values='Block').fillna(0)

# Plot stacked bar for top 10 states by over-exploited blocks
state_summary = state_summary.sort_values('OVER EXPLOITED', ascending=False)

fig, ax = plt.subplots(figsize=(12, 8))
state_summary.head(15).plot(
    kind='bar', stacked=True, ax=ax,
    color=[status_colors.get(c, 'gray') for c in state_summary.columns]
)
ax.set_title("Groundwater Block Status by State (CGWB 2022)")
ax.set_xlabel("State")
ax.set_ylabel("Number of Blocks")
ax.legend(loc='upper right', fontsize=8)
plt.xticks(rotation=45, ha='right')
plt.tight_layout()
plt.savefig("cgwb_state_status.png", dpi=150)
plt.show()

✏️ Practice Exercise¶

Exercise 3.6 — Is Your Block Running Out of Water?

Goal: Find the groundwater status of every block in your district.

Download CGWB 2022 assessment from cgwb.gov.in
Open in Excel → Filter for your State → Filter for your District
List all blocks and their status (Safe / Semi-Critical / Critical / Over-Exploited)

Questions: - [ ] How many blocks in your district are "Over-Exploited"? - [ ] What % of blocks are "Safe"? - [ ] Is there a geographic pattern — are certain parts of your district more stressed? - [ ] What is the depth to water table in May (pre-monsoon) vs November (post-monsoon) in your taluka?

Cross-reference: Compare with LULC data — are over-exploited blocks also those with more irrigated cropland?

Continue to Chapter 4: Infrastructure & Governance →