In recent years, climate change has significantly increased the frequency of extreme rainfall, where precipitation rates exceed both the average daily rate and the sewerage system’s capacity. Jelgava is particularly vulnerable: it is a flat city situated between two rivers (6032 hectares in total, of which 293 hectares are open water). As the lowest-lying populated area in Latvia (2.0–4.5 m above sea level), Jelgava faces high groundwater levels, which put additional pressure on its drainage and stormwater systems, especially during spring floods.
All this significantly complicates the removal of rainwater, because the relief does not allow water to naturally leave the area; to remove water into rivers, diverting sewer pipes is used, while the drainage system is used to collect fresh water from the drains and drainpipes. Although the city operates more than 2,500 gullies, a rainwater drainage network of ~143 km, and 12 large collectors, the system is often overwhelmed. It can manage precipitation up to 15–20 mm, but during short and heavy rainstorms of 30–50 mm and more, the system floods, leaving streets and low-lying areas submerged.
