.infiltration-calculator-wrapper {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
max-width: 800px;
margin: 0 auto;
padding: 20px;
background: #f9f9f9;
border: 1px solid #e0e0e0;
border-radius: 8px;
color: #333;
}
.calc-header {
text-align: center;
margin-bottom: 30px;
}
.calc-header h2 {
margin: 0;
color: #2c3e50;
}
.calc-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
}
@media (max-width: 600px) {
.calc-grid {
grid-template-columns: 1fr;
}
}
.input-group {
margin-bottom: 15px;
}
.input-group label {
display: block;
margin-bottom: 5px;
font-weight: 600;
font-size: 0.9em;
color: #555;
}
.input-group input, .input-group select {
width: 100%;
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
.input-group input:focus {
border-color: #3498db;
outline: none;
}
.calc-btn {
grid-column: 1 / -1;
background-color: #2980b9;
color: white;
border: none;
padding: 15px;
font-size: 18px;
font-weight: bold;
border-radius: 4px;
cursor: pointer;
transition: background-color 0.3s;
margin-top: 10px;
}
.calc-btn:hover {
background-color: #1a5276;
}
.result-section {
grid-column: 1 / -1;
margin-top: 25px;
padding: 20px;
background-color: #fff;
border: 1px solid #ddd;
border-radius: 4px;
display: none;
}
.result-row {
display: flex;
justify-content: space-between;
align-items: center;
padding: 10px 0;
border-bottom: 1px solid #eee;
}
.result-row:last-child {
border-bottom: none;
}
.result-label {
font-weight: 500;
color: #666;
}
.result-value {
font-weight: 700;
color: #2c3e50;
font-size: 1.2em;
}
.soil-classification {
background-color: #e8f6f3;
color: #0e6251;
padding: 15px;
border-radius: 4px;
margin-top: 15px;
text-align: center;
font-weight: bold;
}
.article-content {
max-width: 800px;
margin: 40px auto;
line-height: 1.6;
color: #444;
font-family: sans-serif;
}
.article-content h2 {
color: #2c3e50;
border-bottom: 2px solid #3498db;
padding-bottom: 10px;
margin-top: 30px;
}
.article-content h3 {
color: #34495e;
margin-top: 25px;
}
.article-content ul {
background: #fff;
padding: 20px 40px;
border-radius: 5px;
border: 1px solid #eee;
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.article-content li {
margin-bottom: 10px;
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.formula-box {
background: #ecf0f1;
padding: 15px;
border-left: 5px solid #bdc3c7;
font-family: monospace;
font-size: 1.1em;
margin: 20px 0;
}
function updateLabels() {
var unit = document.getElementById('unitSystem').value;
var labelInitial = document.getElementById('lblInitial');
var labelFinal = document.getElementById('lblFinal');
if (unit === 'mm') {
labelInitial.innerText = 'Initial Water Level (mm)';
labelFinal.innerText = 'Final Water Level (mm)';
} else {
labelInitial.innerText = 'Initial Water Level (in)';
labelFinal.innerText = 'Final Water Level (in)';
}
}
function calculateInfiltration() {
// Get Inputs
var unit = document.getElementById('unitSystem').value;
var timeStr = document.getElementById('timeElapsed').value;
var initStr = document.getElementById('initialLevel').value;
var finalStr = document.getElementById('finalLevel').value;
// Parse Inputs
var time = parseFloat(timeStr);
var initial = parseFloat(initStr);
var final = parseFloat(finalStr);
// Validation
if (isNaN(time) || isNaN(initial) || isNaN(final)) {
alert("Please enter valid numerical values for all fields.");
return;
}
if (time Drop 10mm.
// If drop is negative (e.g. Start 10mm from top, End 20mm from top), we take absolute value.
drop = Math.abs(drop);
// Calculate Rate per minute then convert to per hour
var ratePerMin = drop / time;
var ratePerHour = ratePerMin * 60;
// Display Results
var resultDiv = document.getElementById('results');
var dropDisplay = document.getElementById('resDrop');
var rateDisplay = document.getElementById('resRate');
var textureDisplay = document.getElementById('resTexture');
var soilClassBox = document.getElementById('soilClassBox');
resultDiv.style.display = 'block';
if (unit === 'mm') {
dropDisplay.innerHTML = drop.toFixed(1) + " mm";
rateDisplay.innerHTML = ratePerHour.toFixed(2) + " mm/hr";
// FAO Soil Classification (mm/hr)
if (ratePerHour >= 30) {
textureDisplay.innerHTML = "Rapid (Sand / Sandy Loam)";
soilClassBox.style.backgroundColor = "#d4efdf"; // Green
soilClassBox.style.color = "#0b5345";
} else if (ratePerHour >= 15) {
textureDisplay.innerHTML = "Moderately Rapid (Loam / Silt Loam)";
soilClassBox.style.backgroundColor = "#fcf3cf"; // Yellow
soilClassBox.style.color = "#7d6608";
} else if (ratePerHour >= 5) {
textureDisplay.innerHTML = "Moderate (Clay Loam)";
soilClassBox.style.backgroundColor = "#fae5d3"; // Orange
soilClassBox.style.color = "#873600";
} else {
textureDisplay.innerHTML = "Slow / Very Slow (Clay)";
soilClassBox.style.backgroundColor = "#fadbd8"; // Red
soilClassBox.style.color = "#78281f";
}
} else {
dropDisplay.innerHTML = drop.toFixed(2) + " in";
rateDisplay.innerHTML = ratePerHour.toFixed(2) + " in/hr";
// USDA/FAO Approx conversion to inches (1 inch = 25.4mm)
// 30mm ~= 1.18 in
// 15mm ~= 0.6 in
// 5mm ~= 0.2 in
if (ratePerHour >= 1.18) {
textureDisplay.innerHTML = "Rapid (Sand / Sandy Loam)";
soilClassBox.style.backgroundColor = "#d4efdf";
soilClassBox.style.color = "#0b5345";
} else if (ratePerHour >= 0.6) {
textureDisplay.innerHTML = "Moderately Rapid (Loam / Silt Loam)";
soilClassBox.style.backgroundColor = "#fcf3cf";
soilClassBox.style.color = "#7d6608";
} else if (ratePerHour >= 0.2) {
textureDisplay.innerHTML = "Moderate (Clay Loam)";
soilClassBox.style.backgroundColor = "#fae5d3";
soilClassBox.style.color = "#873600";
} else {
textureDisplay.innerHTML = "Slow / Very Slow (Clay)";
soilClassBox.style.backgroundColor = "#fadbd8";
soilClassBox.style.color = "#78281f";
}
}
}
How to Calculate Infiltration Rate
Understanding soil infiltration rate is crucial for efficient irrigation planning, drainage system design, and managing stormwater runoff. The infiltration rate represents the velocity at which water enters the soil profile. Knowing this metric helps farmers, engineers, and landscapers determine how much water to apply and how fast, preventing waterlogging or wasteful runoff.
The Infiltration Rate Formula
The basic calculation for infiltration rate is derived from measuring the drop in water level over a specific period of time. While complex models like Horton's equation exist for theoretical modeling, field measurements typically use the following simple logic:
Infiltration Rate (I) = ΔH / t
Where:
- I = Infiltration Rate (mm/hr or in/hr)
- ΔH = Change in water height (Drop in level)
- t = Time interval needed for the drop
For example, if the water level in a test ring drops 10mm in 15 minutes, the calculation would be:
(10 mm / 15 min) × 60 min/hr = 40 mm/hr
Measuring Methods: The Double Ring Infiltrometer
The most standard method for calculating infiltration rate in the field is the Double Ring Infiltrometer. This tool consists of two concentric metal rings driven into the soil.
- Setup: Drive both rings into the ground and fill them with water.
- Purpose of Outer Ring: The outer ring acts as a buffer. It forces the water in the inner ring to infiltrate vertically rather than spreading horizontally, ensuring a more accurate vertical infiltration rate measurement.
- Measurement: You record the water level in the inner ring, wait for a specific time interval (e.g., 15 minutes), and record the level again.
Interpreting Infiltration Results
The rate at which soil absorbs water varies drastically depending on soil texture and structure. Below is a general guide to interpreting your results:
- Rapid (> 30 mm/hr): Typical of sandy soils with large pores. Water drains quickly, which is good for drainage but may require frequent irrigation.
- Moderately Rapid (15–30 mm/hr): Often associated with sandy loams. This is generally favorable for many agricultural crops.
- Moderate (5–15 mm/hr): Typical of loamy soils. These soils hold water well while still allowing excess to drain.
- Slow (< 5 mm/hr): Common in soils with high clay content. These soils are prone to waterlogging and surface runoff during heavy rains.
Factors Affecting Infiltration
Several physical factors can alter your calculation results:
- Soil Texture: Sand absorbs water faster than clay.
- Soil Compaction: Heavily trafficked areas (by machinery or livestock) have reduced pore space, significantly lowering infiltration rates.
- Moisture Content: Dry soil initially absorbs water faster (sorption) than soil that is already saturated.
- Organic Matter: High organic matter improves soil structure and porosity, generally increasing the infiltration rate.
Why is this calculation important?
If your irrigation system applies water at 20 mm/hr, but your soil's infiltration rate is only 10 mm/hr, 50% of that water will not enter the root zone immediately. Instead, it will pool on the surface and potentially run off, carrying fertilizers and topsoil with it. By calculating the correct rate, you can match your irrigation delivery to the soil's capacity to absorb it.