Distance to Nearest Drainage Module¶

File: computing/misc/distancetonearestdrainage.py

Overview¶

This module generates distance to nearest drainage line raster layers by clipping pan-India drainage distance data to specific block boundaries. It provides distance measurements from each pixel to the nearest upstream drainage line.

Purpose¶

Processes drainage proximity data for: - Hydrological analysis - Water resource planning - Watershed characterization - Distributes to GEE, GeoServer (via GCS), and database

Architecture¶

flowchart TD
    A[Celery Task Triggered] --> B[ee_initialize]
    B --> C[Build Description & Asset ID]
    C --> D[Load MWS ROI]
    D --> E[Load Pan-India Distance Raster]
    E --> F[Clip to ROI]
    F --> G[Call Raster Generation Function]
    G --> H{Asset Exists?}
    H -->|No| I[Export Raster to GEE]
    I --> J[Check Task Status]
    J --> K[Sync to GCS]
    K --> L[Sync GCS to GeoServer]
    L --> M[save_layer_info_to_db]
    M --> N[make_asset_public]
    N --> O{Success?}
    O -->|Yes| P[Update Sync Status]
    P --> Q[Return True]
    H -->|Yes| R[Skip Export]
    R --> K

Components¶

Main Task: generate_distance_to_nearest_drainage_line()¶

Location: Line 22

Parameters: | Parameter | Type | Description | |-----------|------|-------------| | state | str | State name | | district | str | District name | | block | str | Block/tehsil name | | gee_account_id | int | GEE account identifier |

Returns: bool - Whether layer was successfully synced to GeoServer

Helper Function: distance_to_drainage_line_raster_generation()¶

Location: Line 52

Handles the raster export and synchronization logic.

Parameters: | Parameter | Type | Description | |-----------|------|-------------| | state | str | State name | | district | str | District name | | block | str | Block name | | description | str | Layer description | | roi | ee.FeatureCollection | Region of interest | | raster | ee.Image | Clipped raster image |

Processing Logic¶

1. ROI Definition¶

roi = ee.FeatureCollection(
    get_gee_asset_path(state, district, block)
    + "filtered_mws_"
    + valid_gee_text(district.lower())
    + "_"
    + valid_gee_text(block.lower())
    + "_uid"
)

2. Data Source¶

distance_upsream_dl = ee.Image(DISTANCE_TO_UPSTREAM_DL)  # From constants.pan_india_urls

3. Raster Processing¶

raster = distance_upsream_dl.clip(roi.geometry())

Integration Points¶

computing/misc/distancetonearestdrainage.py
├── computing.utils
│   ├── save_layer_info_to_db()   # Database persistence
│   └── update_layer_sync_status() # Status tracking
├── utilities.gee_utils
│   ├── ee_initialize()           # GEE authentication
│   ├── check_task_status()       # Task monitoring
│   ├── valid_gee_text()          # Text sanitization
│   ├── get_gee_asset_path()      # Asset path generation
│   ├── is_gee_asset_exists()     # Asset existence check
│   ├── sync_raster_to_gcs()      # GCS synchronization
│   ├── sync_raster_gcs_to_geoserver() # GeoServer sync
│   ├── export_raster_asset_to_gee() # Raster export
│   └── make_asset_public()       # ACL management
└── constants.pan_india_urls
    └── DISTANCE_TO_UPSTREAM_DL   # Pan-India drainage distance URL

Output¶

Dataset Name: Distance to Drainage Line

Style Name: distance_nearest_upstream_DL

Raster Sync Workflow¶

This module follows the Raster Sync Pattern:

flowchart LR
    A[GEE Raster Asset] --> B[sync_raster_to_gcs]
    B --> C[Google Cloud Storage]
    C --> D[sync_raster_gcs_to_geoserver]
    D --> E[GeoServer WMS/WCS]

Usage¶

from computing.misc.distancetonearestdrainage import generate_distance_to_nearest_drainage_line

result = generate_distance_to_nearest_drainage_line.delay(
    state="Rajasthan",
    district="Jaipur",
    block="Sanganer",
    gee_account_id=1
)

Pattern Classification¶

This module follows the Simple Raster Clip Pattern:

flowchart TD
    subgraph Pattern
        A[Load Pan-India Raster] --> B[Load ROI]
        B --> C[Clip Raster]
        C --> D[Export to GEE]
        D --> E[Sync to GCS]
        E --> F[Sync to GeoServer]
    end

This pattern is shared with: - naturaldepression.py - slope_percentage.py - catchment_area.py

Dependencies¶

• ee (Google Earth Engine Python API)
• Celery - Distributed task queue