US Sewersheds

Process and analyze US sewershed data from the Clean Watersheds Needs Survey (CWNS).

Overview

This repository includes code to visualize sewershed interconnections in the US based on the 2022 Clean Watershed Needs Survey. The us_sewersheds folder includes two scripts:

Data Processing Logic

The system handles facility relationships using a nested facility types structure:

1. Multi-type Facilities: Some facilities have multiple types (e.g., Treatment Plant + Collection + Reuse). Instead of creating separate dummy IDs, each facility now contains a nested TYPES array where each type is a separate node with its own coordinates and properties:

   • Processing Order: Collection Systems (order 0) → Interceptor Systems (order 1) → Treatment Plants (order 3) → Water Reuse (order 5) → Outfalls (order 6)
   • Coordinate Spacing: Each facility type gets slightly offset coordinates for visual separation
   • Node IDs: Use format CWNS_ID_type_X where X is the index in the TYPES array

2. Final Discharges: Creates additional facility type nodes for discharges to the environment (not to other facilities). Each unique discharge type gets a separate node with facility type determined by discharge type keywords (e.g., "Reuse", "Ocean Discharge").

3. Connection Logic:

   • External Connections: Between different CWNS_IDs using connection rules to select appropriate source/target facility types
   • Internal Connections: Between facility types within the same CWNS_ID based on processing order
   • Mass Balance: Internal flow percentages calculated as 100% minus external flow to maintain mass balance

4. Deduplication: Uses set-based operations throughout to automatically prevent duplicate connections and nodes.

5. merge_cwns_data.py

   • Merges multiple sources for population served into the primary facilities list.
   • Functions:
     • main(state=None): Main processing function that can process all states or a single state.
     • process_multi_type_facilities(data): Creates nested facility types structure for multi-type facilities.
     • create_sewershed_map(data, processed_facilities): Creates network connections between facilities.
   • Required inputs:
     • data/2022CWNS_NATIONAL_APR2024: Clean Watersheds Needs Survey 2022 dataset
       • FACILITIES.csv: Main facilities data
       • FACILITY_PERMIT.csv: Facility permit information
       • AREAS_COUNTY.csv: County area information
       • FACILITY_TYPES.csv: Facility type information
       • FLOW.csv: Flow data
       • POPULATION_WASTEWATER.csv: Wastewater population data
       • POPULATION_WASTEWATER_CONFIRMED.csv: Confirmed wastewater population data
       • POPULATION_DECENTRALIZED.csv: Decentralized population data
       • DISCHARGES.csv: Discharge information

6. sewersheds_app.py

   • Deploys Streamlit application to visualize different sewersheds in the US, by state and county
   • Supports both Network Graph (hierarchical) and Network Map (geographic) views

Installation

From PyPI

pip install us-sewersheds

From Source