The paper by Hans Röthlisberger explores the hydrological dynamics of water flowing within and beneath glaciers. The author models the frictional heat generated by water flowing through tubular channels inside glaciers, which melts the ice walls. However, these channels also tend to close under the overburden pressure. Using an equilibrium equation where the amount of ice melted equals the amount of ice flowing in, differential equations are derived to describe steady flow in horizontal, inclined, and vertical channels at variable depths and with variable discharge, ice properties, and channel roughness. The key findings include: 1. **Pressure and Flow Dynamics**: The pressure decreases with increasing discharge, indicating that water flows in main arteries. This is supported by the observation that certain glacier lakes above long, flat valley glaciers form during low discharge and empty when the discharge is high. 2. **Ice Mass Behavior**: Under the model's conditions, an ice mass of uniform thickness does not float, meaning there is no water layer at the bottom when the bed is inclined downstream. However, it can float on a horizontal bed if the exponent \( n \) in the ice creep law is small. 3. **Coexistence of Channel Types**: The model shows that basal streams (bottom conduits) and lateral streams at the hydraulic grade line (gradient conduits) can coexist. 4. **Time-Dependent and Topographic Effects**: The theory does not account for time-dependent flow, local topography, ice motion, and sediment load, which are crucial factors influencing actual water flow paths. 5. **Computations and Examples**: The paper includes computational results for the Gornergletscher, where bed topography and subglacial water pressure data are available. The study provides insights into the complex dynamics of water flow within and beneath glaciers, highlighting the importance of considering various factors such as ice flow properties, channel characteristics, and overburden pressure.The paper by Hans Röthlisberger explores the hydrological dynamics of water flowing within and beneath glaciers. The author models the frictional heat generated by water flowing through tubular channels inside glaciers, which melts the ice walls. However, these channels also tend to close under the overburden pressure. Using an equilibrium equation where the amount of ice melted equals the amount of ice flowing in, differential equations are derived to describe steady flow in horizontal, inclined, and vertical channels at variable depths and with variable discharge, ice properties, and channel roughness. The key findings include: 1. **Pressure and Flow Dynamics**: The pressure decreases with increasing discharge, indicating that water flows in main arteries. This is supported by the observation that certain glacier lakes above long, flat valley glaciers form during low discharge and empty when the discharge is high. 2. **Ice Mass Behavior**: Under the model's conditions, an ice mass of uniform thickness does not float, meaning there is no water layer at the bottom when the bed is inclined downstream. However, it can float on a horizontal bed if the exponent \( n \) in the ice creep law is small. 3. **Coexistence of Channel Types**: The model shows that basal streams (bottom conduits) and lateral streams at the hydraulic grade line (gradient conduits) can coexist. 4. **Time-Dependent and Topographic Effects**: The theory does not account for time-dependent flow, local topography, ice motion, and sediment load, which are crucial factors influencing actual water flow paths. 5. **Computations and Examples**: The paper includes computational results for the Gornergletscher, where bed topography and subglacial water pressure data are available. The study provides insights into the complex dynamics of water flow within and beneath glaciers, highlighting the importance of considering various factors such as ice flow properties, channel characteristics, and overburden pressure.