luokai0 Hydrology Expert
Before Starting
- Surface water or groundwater?
- Flood, drought, or water quality focus?
- Research or engineering application?
Core Expertise Areas
Water Cycle
Precipitation: rain, snow, hail — measured by rain gauges and radar. Evapotranspiration: evaporation plus plant transpiration, largest water loss. Infiltration: water entry into soil — controlled by soil type, moisture, vegetation. Runoff: surface flow to streams — generated when precipitation exceeds infiltration. Groundwater recharge: infiltrated water reaching saturated zone.
Surface Water
Streamflow: discharge Q = A x V, measured at gauging stations. Rating curve: relationship between stage and discharge at a gauging site. Hydrograph: streamflow vs time response to precipitation event. Unit hydrograph: 1 cm of effective rainfall over watershed in unit time. Base flow: groundwater contribution to streamflow during dry periods.
Groundwater
Aquifer types: unconfined (water table), confined (artesian), perched. Darcy law: Q = -KA dh/dl, K is hydraulic conductivity. Hydraulic head: elevation head plus pressure head. Theis equation: drawdown around pumping well in confined aquifer. Groundwater flow equation: combines Darcy law and continuity.
Flood Hydrology
Return period: 100-year flood has 1% chance of exceedance in any year. Frequency analysis: fit probability distribution to annual maximum flows. Flood routing: tracking flood wave through channel or reservoir. Rational method: Q = CiA for small watersheds, C is runoff coefficient.
Best Practices
- Always perform quality control on streamflow records
- Use multiple methods for evapotranspiration estimation
- Account for land use change effects on hydrology
- Consider climate change projections in water resource planning
Common Pitfalls
| Pitfall | Fix |
|---|---|
| Confusing return period with probability | 100-year flood does not mean once per century |
| Ignoring baseflow separation | Stormflow and baseflow behave differently |
| Applying Darcy law to turbulent flow | Check Reynolds number for flow regime |
| Assuming stationarity in frequency analysis | Climate change may shift flood frequency |
Related Skills
- geology-expert
- meteorology-expert
- oceanography-expert