水量平衡计算 | Water Balance Calculation

Per-pixel water balance computation, with the core equation:

P = ET + Q + ΔS

i.e. Precipitation = Evapotranspiration + Runoff + Change in Storage. For each pixel, every component is computed independently and the closure residual is derived:

residual = P − ET − Q − ΔS

Under perfect closure the residual is 0; with real observational data a residual remains because the components come from different sources (precipitation station networks, remote-sensing evapotranspiration products, hydrological model runoff, gravity-satellite storage change). This skill uses the relative closure error (mean|residual| / mean P) to quantify data consistency — a common way to diagnose the quality of multi-source hydrological data and identify systematic biases, applicable to watershed water-balance diagnosis, cross-validation of remote-sensing products, and quality assessment prior to data assimilation.

The --synthetic mode generates a complete dataset that is physically closed (ET≈0.45P, Q≈0.30P, ΔS as the closing residual, plus observational perturbation with std≈3 mm), so the pipeline can be validated without network access or real data; the relative closure error of synthetic data should be < 2%.

Dependencies / 依赖

pip install numpy rasterio scipy

Usage / 使用方法

Basic Usage (Synthetic Data, Offline)

python geoskill-water-balance-calculation.py --bbox 116.0 39.0 117.0 40.0 --output-dir ./output

Example 1: Synthetic Data Water Balance

python geoskill-water-balance-calculation.py \
    --bbox 116.0 39.0 117.0 40.0 \
    --synthetic \
    --output-dir ./wb_syn

Example 2: Real Precipitation Raster (Demo Mode)

python geoskill-water-balance-calculation.py \
    --input precip_annual.tif \
    --output-dir ./wb_real

(With the input precipitation as P, the remaining components are synthesized in empirical proportions to demonstrate the workflow.)

Example 3: Different Regions

python geoskill-water-balance-calculation.py --bbox 121 31 122 32 --synthetic --output-dir ./wb_sh --quiet

Example 4: Minimal Region

python geoskill-water-balance-calculation.py --bbox 116.39 39.90 116.40 39.91 --synthetic --output-dir ./wb_tiny --quiet

Output / 输出

Data Source / 数据源 / Source

• Precipitation P: local GeoTIFF, or from CHIRPS / GPM / ground stations
• ET / Q / ΔS: generated in synthetic mode; real applications can integrate MODIS ET, hydrological models, GRACE, etc.
• Synthetic mode: generated locally, no external data source

Privacy / 隐私声明 / Privacy

• Fully offline by default; no network requests are made
• --synthetic mode reads no external data
• All computation is done locally; no user data is uploaded

License / License

MIT

name: geoskill-water-balance-calculation description: '逐像元水量平衡计算 P = ET + Q + ΔS，评估闭合差。Per-pixel water balance computation P = ET + Q + ΔS with closure residual assessment. 输出各分量/闭合差 GeoTIFF + 报告 JSON。'

水量平衡计算 | Water Balance Calculation

逐像元水量平衡计算，核心方程：

P = ET + Q + ΔS

即 降水 = 蒸散发 + 径流 + 蓄水变化。对每个像元独立计算各分量，并求闭合差 （closure residual）：

residual = P − ET − Q − ΔS

理想闭合时残差为 0；真实观测数据因各分量来自不同数据源（降水站网、遥感蒸散发 产品、水文模型径流、重力卫星蓄水变化）而存在残差。本 skill 用相对闭合误差 （mean|residual| / mean P）量化数据一致性，是诊断多源水文数据质量、识别系统 偏差的常用手段，适用于流域水平衡诊断、遥感产品交叉验证、数据同化前的质量评估。

支持 --synthetic 模式生成物理闭合（ET≈0.45P、Q≈0.30P、ΔS 为闭合残值， 再叠加 std≈3 mm 的观测扰动）的完整数据集，无需网络和真实数据即可验证流程， 合成数据的相对闭合误差应 < 2%。

依赖

pip install numpy rasterio scipy

使用方法

基本用法（合成数据，离线）

python geoskill-water-balance-calculation.py --bbox 116.0 39.0 117.0 40.0 --output-dir ./output

示例 1：合成数据水量平衡

python geoskill-water-balance-calculation.py \
    --bbox 116.0 39.0 117.0 40.0 \
    --synthetic \
    --output-dir ./wb_syn

示例 2：真实降水栅格（演示模式）

python geoskill-water-balance-calculation.py \
    --input precip_annual.tif \
    --output-dir ./wb_real

（以输入降水为 P，其余分量按经验比例合成以演示流程。）

示例 3：不同区域

python geoskill-water-balance-calculation.py --bbox 121 31 122 32 --synthetic --output-dir ./wb_sh --quiet

示例 4：极小区域

python geoskill-water-balance-calculation.py --bbox 116.39 39.90 116.40 39.91 --synthetic --output-dir ./wb_tiny --quiet

输出

数据源 / Source

• 降水 P：本地 GeoTIFF，或来自 CHIRPS / GPM / 地面站点
• ET / Q / ΔS：合成模式生成；真实应用可接入 MODIS ET、水文模型、GRACE 等
• 合成模式：本地生成，无外部数据源

隐私声明 / Privacy

• 默认完全离线运行，不发起任何网络请求
• --synthetic 模式不读取任何外部数据
• 所有计算在本地完成，不上传用户数据

License

MIT